20111221999931 has 2 divisors, whose sum is σ = 20111221999932. Its totient is φ = 20111221999930.

The previous prime is 20111221999907. The next prime is 20111222000027. The reversal of 20111221999931 is 13999912211102.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20111221999931 is a prime.

It is a super-2 number, since 2×20111221999931² (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 20111221999931.

It is not a weakly prime, because it can be changed into another prime (20111221999031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055610999965 + 10055610999966.

It is an arithmetic number, because the mean of its divisors is an integer number (10055610999966).

Almost surely, 2^{20111221999931} is an apocalyptic number.

20111221999931 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111221999931 is an equidigital number, since it uses as much as digits as its factorization.

20111221999931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 157464, while the sum is 50.

The spelling of 20111221999931 in words is "twenty trillion, one hundred eleven billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred thirty-one".