21231011957 has 2 divisors, whose sum is σ = 21231011958. Its totient is φ = 21231011956.

The previous prime is 21231011947. The next prime is 21231012041. The reversal of 21231011957 is 75911013212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20166556081 + 1064455876 = 142009^2 + 32626^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231011957 - 2¹⁴ = 21230995573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21231011947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615505978 + 10615505979.

It is an arithmetic number, because the mean of its divisors is an integer number (10615505979).

Almost surely, 2^21231011957 is an apocalyptic number.

It is an amenable number.

21231011957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231011957 is an equidigital number, since it uses as much as digits as its factorization.

21231011957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 32.

The spelling of 21231011957 in words is "twenty-one billion, two hundred thirty-one million, eleven thousand, nine hundred fifty-seven".