630731721 has 4 divisors (see below), whose sum is σ = 840975632. Its totient is φ = 420487812.

The previous prime is 630731707. The next prime is 630731819. The reversal of 630731721 is 127137036.

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 not a de Polignac number, because 630731721 - 2⁷ = 630731593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (630730721) 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, 105121951 + ... + 105121956.

It is an arithmetic number, because the mean of its divisors is an integer number (210243908).

Almost surely, 2^630731721 is an apocalyptic number.

It is an amenable number.

630731721 is a deficient number, since it is larger than the sum of its proper divisors (210243911).

630731721 is a wasteful number, since it uses less digits than its factorization.

630731721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210243910.

The product of its (nonzero) digits is 5292, while the sum is 30.

The square root of 630731721 is about 25114.3727972649. The cubic root of 630731721 is about 857.5936521626.

Adding to 630731721 its reverse (127137036), we get a palindrome (757868757).

The spelling of 630731721 in words is "six hundred thirty million, seven hundred thirty-one thousand, seven hundred twenty-one".