631256281891 has 2 divisors, whose sum is σ = 631256281892. Its totient is φ = 631256281890.

The previous prime is 631256281889. The next prime is 631256281927. The reversal of 631256281891 is 198182652136.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 631256281891 - 2¹ = 631256281889 is a prime.

Together with 631256281889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (631256281811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315628140945 + 315628140946.

It is an arithmetic number, because the mean of its divisors is an integer number (315628140946).

Almost surely, 2^631256281891 is an apocalyptic number.

631256281891 is a deficient number, since it is larger than the sum of its proper divisors (1).

631256281891 is an equidigital number, since it uses as much as digits as its factorization.

631256281891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 52.

The spelling of 631256281891 in words is "six hundred thirty-one billion, two hundred fifty-six million, two hundred eighty-one thousand, eight hundred ninety-one".