21661016632601 has 16 divisors (see below), whose sum is σ = 22810904054400. Its totient is φ = 20512114247808.

The previous prime is 21661016632597. The next prime is 21661016632613. The reversal of 21661016632601 is 10623661016612.

It is a cyclic number.

It is not a de Polignac number, because 21661016632601 - 2² = 21661016632597 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661016632621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 697309796 + ... + 697340858.

It is an arithmetic number, because the mean of its divisors is an integer number (1425681503400).

Almost surely, 2^{21661016632601} is an apocalyptic number.

It is an amenable number.

21661016632601 is a deficient number, since it is larger than the sum of its proper divisors (1149887421799).

21661016632601 is a wasteful number, since it uses less digits than its factorization.

21661016632601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45728.

The product of its (nonzero) digits is 93312, while the sum is 41.

The spelling of 21661016632601 in words is "twenty-one trillion, six hundred sixty-one billion, sixteen million, six hundred thirty-two thousand, six hundred one".