21210912990 has 32 divisors (see below), whose sum is σ = 56562435360. Its totient is φ = 5656243392.

The previous prime is 21210912959. The next prime is 21210913013. The reversal of 21210912990 is 9921901212.

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 15 ways as a sum of consecutive naturals, for example, 39279199 + ... + 39279738.

It is an arithmetic number, because the mean of its divisors is an integer number (1767576105).

Almost surely, 2^21210912990 is an apocalyptic number.

21210912990 is an abundant number, since it is smaller than the sum of its proper divisors (35351522370).

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

21210912990 is a wasteful number, since it uses less digits than its factorization.

21210912990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78558953 (or 78558947 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The spelling of 21210912990 in words is "twenty-one billion, two hundred ten million, nine hundred twelve thousand, nine hundred ninety".