21207686590 has 48 divisors (see below), whose sum is σ = 40615937568. Its totient is φ = 7955110592.

The previous prime is 21207686587. The next prime is 21207686597. The reversal of 21207686590 is 9568670212.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is a self number, because there is not a number n which added to its sum of digits gives 21207686590.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21207686597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16077951 + ... + 16079269.

It is an arithmetic number, because the mean of its divisors is an integer number (846165366).

Almost surely, 2^21207686590 is an apocalyptic number.

21207686590 is a deficient number, since it is larger than the sum of its proper divisors (19408250978).

21207686590 is an equidigital number, since it uses as much as digits as its factorization.

21207686590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2721 (or 1402 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 46.

The spelling of 21207686590 in words is "twenty-one billion, two hundred seven million, six hundred eighty-six thousand, five hundred ninety".