30813721 has 12 divisors (see below), whose sum is σ = 33268480. Its totient is φ = 28508040.

The previous prime is 30813719. The next prime is 30813733. The reversal of 30813721 is 12731803.

It is not a de Polignac number, because 30813721 - 2¹ = 30813719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30813791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15460 + ... + 17338.

Almost surely, 2^30813721 is an apocalyptic number.

30813721 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

30813721 is a deficient number, since it is larger than the sum of its proper divisors (2454759).

30813721 is a wasteful number, since it uses less digits than its factorization.

30813721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1956 (or 1933 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 30813721 is about 5551.0108088527. The cubic root of 30813721 is about 313.5075821454.

The spelling of 30813721 in words is "thirty million, eight hundred thirteen thousand, seven hundred twenty-one".