21601667021604 has 12 divisors (see below), whose sum is σ = 50403889717104. Its totient is φ = 7200555673864.

The previous prime is 21601667021593. The next prime is 21601667021713. The reversal of 21601667021604 is 40612076610612.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21601667021604² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 900069459222 + ... + 900069459245.

It is an arithmetic number, because the mean of its divisors is an integer number (4200324143092).

Almost surely, 2^{21601667021604} is an apocalyptic number.

It is an amenable number.

21601667021604 is an abundant number, since it is smaller than the sum of its proper divisors (28802222695500).

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

21601667021604 is a wasteful number, since it uses less digits than its factorization.

21601667021604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1800138918474 (or 1800138918472 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 42.

The spelling of 21601667021604 in words is "twenty-one trillion, six hundred one billion, six hundred sixty-seven million, twenty-one thousand, six hundred four".