21506777166417 has 32 divisors (see below), whose sum is σ = 31184030592000. Its totient is φ = 13129349050368.

The previous prime is 21506777166389. The next prime is 21506777166421. The reversal of 21506777166417 is 71466177760512.

It is not a de Polignac number, because 21506777166417 - 2¹⁹ = 21506776642129 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21506777166617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 72707584 + ... + 73002782.

It is an arithmetic number, because the mean of its divisors is an integer number (974500956000).

Almost surely, 2^{21506777166417} is an apocalyptic number.

It is an amenable number.

21506777166417 is a deficient number, since it is larger than the sum of its proper divisors (9677253425583).

21506777166417 is a wasteful number, since it uses less digits than its factorization.

21506777166417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333865.

The product of its (nonzero) digits is 20744640, while the sum is 60.

The spelling of 21506777166417 in words is "twenty-one trillion, five hundred six billion, seven hundred seventy-seven million, one hundred sixty-six thousand, four hundred seventeen".