1221520040 has 64 divisors (see below), whose sum is σ = 3133967760. Its totient is φ = 424488960.

The previous prime is 1221520037. The next prime is 1221520099. The reversal of 1221520040 is 400251221.

It can be written as a sum of positive squares in 8 ways, for example, as 730188484 + 491331556 = 27022^2 + 22166^2 .

It is a super-3 number, since 3×1221520040³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60251 + ... + 77930.

Almost surely, 2^1221520040 is an apocalyptic number.

1221520040 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221520040 is an abundant number, since it is smaller than the sum of its proper divisors (1912447720).

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

1221520040 is a wasteful number, since it uses less digits than its factorization.

1221520040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138222 (or 138218 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 1221520040 is about 34950.2509289991. The cubic root of 1221520040 is about 1068.9733186312.

Adding to 1221520040 its reverse (400251221), we get a palindrome (1621771261).

The spelling of 1221520040 in words is "one billion, two hundred twenty-one million, five hundred twenty thousand, forty".