21606490464 has 72 divisors (see below), whose sum is σ = 61415536392. Its totient is φ = 6648145920.

The previous prime is 21606490463. The next prime is 21606490469. The reversal of 21606490464 is 46409460612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606490463) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 649657 + ... + 682104.

It is an arithmetic number, because the mean of its divisors is an integer number (852993561).

Almost surely, 2^21606490464 is an apocalyptic number.

21606490464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21606490464 is an abundant number, since it is smaller than the sum of its proper divisors (39809045928).

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

21606490464 is a wasteful number, since it uses less digits than its factorization.

21606490464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331800 (or 1331779 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 42.

The spelling of 21606490464 in words is "twenty-one billion, six hundred six million, four hundred ninety thousand, four hundred sixty-four".