21003260656 has 40 divisors (see below), whose sum is σ = 46958772224. Its totient is φ = 8914000320.

The previous prime is 21003260651. The next prime is 21003260693. The reversal of 21003260656 is 65606230012.

It is a super-2 number, since 2×21003260656² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003260651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 898800 + ... + 921871.

Almost surely, 2^21003260656 is an apocalyptic number.

It is an amenable number.

21003260656 is an abundant number, since it is smaller than the sum of its proper divisors (25955511568).

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

21003260656 is a wasteful number, since it uses less digits than its factorization.

21003260656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1820789 (or 1820783 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

Adding to 21003260656 its reverse (65606230012), we get a palindrome (86609490668).

The spelling of 21003260656 in words is "twenty-one billion, three million, two hundred sixty thousand, six hundred fifty-six".