21664328616468 has 18 divisors (see below), whose sum is σ = 54762608447274. Its totient is φ = 7221442872144.

The previous prime is 21664328616449. The next prime is 21664328616487. The reversal of 21664328616468 is 86461682346612.

21664328616468 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 4 + 3 + 2 + 8 + 616 + 4 + 6 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (21664328616449) and next prime (21664328616487).

It can be written as a sum of positive squares in only one way, i.e., 19686063862404 + 1978264754064 = 4436898^2 + 1406508^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 300893452971 + ... + 300893453042.

Almost surely, 2^{21664328616468} is an apocalyptic number.

It is an amenable number.

21664328616468 is an abundant number, since it is smaller than the sum of its proper divisors (33098279830806).

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

21664328616468 is a wasteful number, since it uses less digits than its factorization.

21664328616468 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601786906023 (or 601786906018 counting only the distinct ones).

The product of its digits is 95551488, while the sum is 63.

The spelling of 21664328616468 in words is "twenty-one trillion, six hundred sixty-four billion, three hundred twenty-eight million, six hundred sixteen thousand, four hundred sixty-eight".