30921072 has 80 divisors (see below), whose sum is σ = 98327040. Its totient is φ = 8153856.

The previous prime is 30921067. The next prime is 30921089. The reversal of 30921072 is 27012903.

It is a super-2 number, since 2×30921072² = 1912225387258368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 829 + ... + 7907.

It is an arithmetic number, because the mean of its divisors is an integer number (1229088).

Almost surely, 2^30921072 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 30921072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49163520).

30921072 is an abundant number, since it is smaller than the sum of its proper divisors (67405968).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

30921072 is a wasteful number, since it uses less digits than its factorization.

30921072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7110 (or 7104 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 24.

The square root of 30921072 is about 5560.6719018478. The cubic root of 30921072 is about 313.8712333935.

Adding to 30921072 its reverse (27012903), we get a palindrome (57933975).

The spelling of 30921072 in words is "thirty million, nine hundred twenty-one thousand, seventy-two".