21243791256 has 32 divisors (see below), whose sum is σ = 53118587760. Its totient is φ = 7080049152.

The previous prime is 21243791249. The next prime is 21243791279. The reversal of 21243791256 is 65219734212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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, 72876 + ... + 218628.

Almost surely, 2^21243791256 is an apocalyptic number.

It is a pronic number, being equal to 145752×145753.

It is an amenable number.

21243791256 is an abundant number, since it is smaller than the sum of its proper divisors (31874796504).

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

21243791256 is a wasteful number, since it uses less digits than its factorization.

21243791256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151835 (or 151831 counting only the distinct ones).

The product of its digits is 181440, while the sum is 42.

The spelling of 21243791256 in words is "twenty-one billion, two hundred forty-three million, seven hundred ninety-one thousand, two hundred fifty-six".