1531255513981 has 2 divisors, whose sum is σ = 1531255513982. Its totient is φ = 1531255513980.

The previous prime is 1531255513979. The next prime is 1531255514011. The reversal of 1531255513981 is 1893155521351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1529253756900 + 2001757081 = 1236630^2 + 44741^2 .

It is a cyclic number.

It is not a de Polignac number, because 1531255513981 - 2¹ = 1531255513979 is a prime.

It is a super-2 number, since 2×1531255513981² (a number of 25 digits) contains 22 as substring.

Together with 1531255513979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1531255513181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 765627756990 + 765627756991.

It is an arithmetic number, because the mean of its divisors is an integer number (765627756991).

Almost surely, 2^{1531255513981} is an apocalyptic number.

It is an amenable number.

1531255513981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1531255513981 is an equidigital number, since it uses as much as digits as its factorization.

1531255513981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 810000, while the sum is 49.

The spelling of 1531255513981 in words is "one trillion, five hundred thirty-one billion, two hundred fifty-five million, five hundred thirteen thousand, nine hundred eighty-one".