21660400121166 has 48 divisors (see below), whose sum is σ = 49897695152448. Its totient is φ = 6767222860800.

The previous prime is 21660400121141. The next prime is 21660400121179. The reversal of 21660400121166 is 66112100406612.

21660400121166 is a `hidden beast` number, since 2 + 16 + 60 + 400 + 1 + 21 + 166 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21660400121166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 146784390 + ... + 146931881.

It is an arithmetic number, because the mean of its divisors is an integer number (1039535315676).

Almost surely, 2^{21660400121166} is an apocalyptic number.

21660400121166 is an abundant number, since it is smaller than the sum of its proper divisors (28237295031282).

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

21660400121166 is a wasteful number, since it uses less digits than its factorization.

21660400121166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293716537 (or 293716534 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

Adding to 21660400121166 its reverse (66112100406612), we get a palindrome (87772500527778).

The spelling of 21660400121166 in words is "twenty-one trillion, six hundred sixty billion, four hundred million, one hundred twenty-one thousand, one hundred sixty-six".