631777431721 has 2 divisors, whose sum is σ = 631777431722. Its totient is φ = 631777431720.

The previous prime is 631777431713. The next prime is 631777431731. The reversal of 631777431721 is 127134777136.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 542268759321 + 89508672400 = 736389^2 + 299180^2 .

It is a cyclic number.

It is not a de Polignac number, because 631777431721 - 2³ = 631777431713 is a prime.

It is not a weakly prime, because it can be changed into another prime (631777431731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315888715860 + 315888715861.

It is an arithmetic number, because the mean of its divisors is an integer number (315888715861).

Almost surely, 2^631777431721 is an apocalyptic number.

It is an amenable number.

631777431721 is a deficient number, since it is larger than the sum of its proper divisors (1).

631777431721 is an equidigital number, since it uses as much as digits as its factorization.

631777431721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1037232, while the sum is 49.

The spelling of 631777431721 in words is "six hundred thirty-one billion, seven hundred seventy-seven million, four hundred thirty-one thousand, seven hundred twenty-one".