631913281 has 4 divisors (see below), whose sum is σ = 632828464. Its totient is φ = 630998100.

The previous prime is 631913257. The next prime is 631913287. The reversal of 631913281 is 182319136.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 631913281 - 2²⁹ = 95042369 is a prime.

It is a super-2 number, since 2×631913281² = 798628789408369922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (631913287) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 456555 + ... + 457936.

It is an arithmetic number, because the mean of its divisors is an integer number (158207116).

Almost surely, 2^631913281 is an apocalyptic number.

It is an amenable number.

631913281 is a deficient number, since it is larger than the sum of its proper divisors (915183).

631913281 is an equidigital number, since it uses as much as digits as its factorization.

631913281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 915182.

The product of its digits is 7776, while the sum is 34.

The square root of 631913281 is about 25137.8853724811. The cubic root of 631913281 is about 858.1288328302.

It can be divided in two parts, 6319 and 13281, that added together give a square (19600 = 140²).

The spelling of 631913281 in words is "six hundred thirty-one million, nine hundred thirteen thousand, two hundred eighty-one".