21920405664 has 48 divisors (see below), whose sum is σ = 57575962080. Its totient is φ = 7302370560.

The previous prime is 21920405587. The next prime is 21920405669. The reversal of 21920405664 is 46650402912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (21920405669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91819 + ... + 228629.

It is an arithmetic number, because the mean of its divisors is an integer number (1199499210).

Almost surely, 2^21920405664 is an apocalyptic number.

21920405664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21920405664 is an abundant number, since it is smaller than the sum of its proper divisors (35655556416).

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

21920405664 is a wasteful number, since it uses less digits than its factorization.

21920405664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138493 (or 138485 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 21920405664 in words is "twenty-one billion, nine hundred twenty million, four hundred five thousand, six hundred sixty-four".