21945049831 has 2 divisors, whose sum is σ = 21945049832. Its totient is φ = 21945049830.

The previous prime is 21945049817. The next prime is 21945049877. The reversal of 21945049831 is 13894054912.

It is an a-pointer prime, because the next prime (21945049877) can be obtained adding 21945049831 to its sum of digits (46).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21945049831 - 2⁷ = 21945049703 is a prime.

It is a super-2 number, since 2×21945049831² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21945049801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972524915 + 10972524916.

It is an arithmetic number, because the mean of its divisors is an integer number (10972524916).

Almost surely, 2^21945049831 is an apocalyptic number.

21945049831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945049831 is an equidigital number, since it uses as much as digits as its factorization.

21945049831 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 311040, while the sum is 46.

The spelling of 21945049831 in words is "twenty-one billion, nine hundred forty-five million, forty-nine thousand, eight hundred thirty-one".