21204347956 has 48 divisors (see below), whose sum is σ = 42362812800. Its totient is φ = 9192712320.

The previous prime is 21204347951. The next prime is 21204347963. The reversal of 21204347956 is 65974340212.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204347951) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 323170 + ... + 383206.

It is an arithmetic number, because the mean of its divisors is an integer number (882558600).

Almost surely, 2^21204347956 is an apocalyptic number.

It is an amenable number.

21204347956 is a deficient number, since it is larger than the sum of its proper divisors (21158464844).

21204347956 is a wasteful number, since it uses less digits than its factorization.

21204347956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60424 (or 60422 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 43.

The spelling of 21204347956 in words is "twenty-one billion, two hundred four million, three hundred forty-seven thousand, nine hundred fifty-six".