21906366931681 has 8 divisors (see below), whose sum is σ = 22339537998624. Its totient is φ = 21477225363360.

The previous prime is 21906366931679. The next prime is 21906366931733. The reversal of 21906366931681 is 18613966360912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21906366931681 - 2¹ = 21906366931679 is a prime.

It is a super-2 number, since 2×21906366931681² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21906366931601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1007363676 + ... + 1007385421.

It is an arithmetic number, because the mean of its divisors is an integer number (2792442249828).

Almost surely, 2^{21906366931681} is an apocalyptic number.

It is an amenable number.

21906366931681 is a deficient number, since it is larger than the sum of its proper divisors (433171066943).

21906366931681 is a wasteful number, since it uses less digits than its factorization.

21906366931681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2014749311.

The product of its (nonzero) digits is 15116544, while the sum is 61.

The spelling of 21906366931681 in words is "twenty-one trillion, nine hundred six billion, three hundred sixty-six million, nine hundred thirty-one thousand, six hundred eighty-one".