630721021 has 8 divisors (see below), whose sum is σ = 721270784. Its totient is φ = 540282960.

The previous prime is 630720943. The next prime is 630721027. The reversal of 630721021 is 120127036.

630721021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 630721021 - 2²⁵ = 597166589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 630720983 and 630721001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (630721027) 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, 15450 + ... + 38731.

It is an arithmetic number, because the mean of its divisors is an integer number (90158848).

Almost surely, 2^630721021 is an apocalyptic number.

It is an amenable number.

630721021 is a deficient number, since it is larger than the sum of its proper divisors (90549763).

630721021 is a wasteful number, since it uses less digits than its factorization.

630721021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55851.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 630721021 is about 25114.1597709340. The cubic root of 630721021 is about 857.5888026079.

Adding to 630721021 its reverse (120127036), we get a palindrome (750848057).

The spelling of 630721021 in words is "six hundred thirty million, seven hundred twenty-one thousand, twenty-one".