631511921 has 8 divisors (see below), whose sum is σ = 634396224. Its totient is φ = 628634160.

The previous prime is 631511879. The next prime is 631511927. The reversal of 631511921 is 129115136.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 631511921 - 2⁶ = 631511857 is a prime.

It is a super-2 number, since 2×631511921² = 797614612730220482, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (631511927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 319091 + ... + 321063.

It is an arithmetic number, because the mean of its divisors is an integer number (79299528).

Almost surely, 2^631511921 is an apocalyptic number.

It is an amenable number.

631511921 is a deficient number, since it is larger than the sum of its proper divisors (2884303).

631511921 is a wasteful number, since it uses less digits than its factorization.

631511921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3271.

The product of its digits is 1620, while the sum is 29.

The square root of 631511921 is about 25129.9009349420. The cubic root of 631511921 is about 857.9471140493.

The spelling of 631511921 in words is "six hundred thirty-one million, five hundred eleven thousand, nine hundred twenty-one".