21031312157 has 2 divisors, whose sum is σ = 21031312158. Its totient is φ = 21031312156.

The previous prime is 21031312129. The next prime is 21031312193. The reversal of 21031312157 is 75121313012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20023948036 + 1007364121 = 141506^2 + 31739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21031312157 - 2⁸ = 21031311901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21031315157) 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, 10515656078 + 10515656079.

It is an arithmetic number, because the mean of its divisors is an integer number (10515656079).

Almost surely, 2^21031312157 is an apocalyptic number.

It is an amenable number.

21031312157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21031312157 is an equidigital number, since it uses as much as digits as its factorization.

21031312157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 26.

Adding to 21031312157 its reverse (75121313012), we get a palindrome (96152625169).

The spelling of 21031312157 in words is "twenty-one billion, thirty-one million, three hundred twelve thousand, one hundred fifty-seven".