1221521144 has 32 divisors (see below), whose sum is σ = 2326922400. Its totient is φ = 601084800.

The previous prime is 1221521141. The next prime is 1221521149. The reversal of 1221521144 is 4411251221.

It is a super-2 number, since 2×1221521144² = 2984227810478137472, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221521141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127034 + ... + 136310.

It is an arithmetic number, because the mean of its divisors is an integer number (72716325).

Almost surely, 2^1221521144 is an apocalyptic number.

It is an amenable number.

1221521144 is a deficient number, since it is larger than the sum of its proper divisors (1105401256).

1221521144 is a wasteful number, since it uses less digits than its factorization.

1221521144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9543 (or 9539 counting only the distinct ones).

The product of its digits is 640, while the sum is 23.

The square root of 1221521144 is about 34950.2667228735. The cubic root of 1221521144 is about 1068.9736406743.

Adding to 1221521144 its reverse (4411251221), we get a palindrome (5632772365).

The spelling of 1221521144 in words is "one billion, two hundred twenty-one million, five hundred twenty-one thousand, one hundred forty-four".