1221761312 has 54 divisors (see below), whose sum is σ = 2487000537. Its totient is φ = 590811264.

The previous prime is 1221761297. The next prime is 1221761327. The reversal of 1221761312 is 2131671221.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is an interprime number because it is at equal distance from previous prime (1221761297) and next prime (1221761327).

It can be written as a sum of positive squares in 2 ways, for example, as 985708816 + 236052496 = 31396^2 + 15364^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=24716.

It is a super-2 number, since 2×1221761312² = 2985401406999922688, which contains 22 as substring.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 7315853 + ... + 7316019.

Almost surely, 2^1221761312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221761312

1221761312 is an abundant number, since it is smaller than the sum of its proper divisors (1265239225).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221761312 is an frugal number, since it uses more digits than its factorization.

1221761312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418 (or 206 counting only the distinct ones).

The product of its digits is 1008, while the sum is 26.

The square root of 1221761312 is about 34953.7024076134. The cubic root of 1221761312 is about 1069.0436944316.

Subtracting 1221761312 from its reverse (2131671221), we obtain a palindrome (909909909).

The spelling of 1221761312 in words is "one billion, two hundred twenty-one million, seven hundred sixty-one thousand, three hundred twelve".