30750721 has 4 divisors (see below), whose sum is σ = 32369200. Its totient is φ = 29132244.

The previous prime is 30750691. The next prime is 30750743. The reversal of 30750721 is 12705703.

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 30750721 - 2⁵ = 30750689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30750761) 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, 809211 + ... + 809248.

It is an arithmetic number, because the mean of its divisors is an integer number (8092300).

Almost surely, 2^30750721 is an apocalyptic number.

It is an amenable number.

30750721 is a deficient number, since it is larger than the sum of its proper divisors (1618479).

30750721 is a wasteful number, since it uses less digits than its factorization.

30750721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1618478.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 30750721 is about 5545.3332632043. Note that the first 3 decimals coincide. The cubic root of 30750721 is about 313.2937763805.

The spelling of 30750721 in words is "thirty million, seven hundred fifty thousand, seven hundred twenty-one".