21945691796931 has 24 divisors (see below), whose sum is σ = 36738059514624. Its totient is φ = 12363770023920.

The previous prime is 21945691796869. The next prime is 21945691796969. The reversal of 21945691796931 is 13969719654912.

21945691796931 is a `hidden beast` number, since 2 + 19 + 4 + 569 + 17 + 9 + 6 + 9 + 31 = 666.

It is not a de Polignac number, because 21945691796931 - 2²³ = 21945683408323 is a prime.

It is a super-2 number, since 2×21945691796931² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21945691796931.

It is not an unprimeable number, because it can be changed into a prime (21945691796981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2453124501 + ... + 2453133446.

It is an arithmetic number, because the mean of its divisors is an integer number (1530752479776).

Almost surely, 2^{21945691796931} is an apocalyptic number.

21945691796931 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21945691796931 is a deficient number, since it is larger than the sum of its proper divisors (14792367717693).

21945691796931 is a wasteful number, since it uses less digits than its factorization.

21945691796931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4906258031 (or 4906258028 counting only the distinct ones).

The product of its digits is 198404640, while the sum is 72.

The spelling of 21945691796931 in words is "twenty-one trillion, nine hundred forty-five billion, six hundred ninety-one million, seven hundred ninety-six thousand, nine hundred thirty-one".