721305945 has 64 divisors (see below), whose sum is σ = 1327104000. Its totient is φ = 371487168.

The previous prime is 721305917. The next prime is 721305953. The reversal of 721305945 is 549503127.

It is not a de Polignac number, because 721305945 - 2⁵ = 721305913 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 500536 + ... + 501974.

It is an arithmetic number, because the mean of its divisors is an integer number (20736000).

Almost surely, 2^721305945 is an apocalyptic number.

It is an amenable number.

721305945 is a deficient number, since it is larger than the sum of its proper divisors (605798055).

721305945 is a wasteful number, since it uses less digits than its factorization.

721305945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1579 (or 1573 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 36.

The square root of 721305945 is about 26857.1395535712. The cubic root of 721305945 is about 896.8225172055.

The spelling of 721305945 in words is "seven hundred twenty-one million, three hundred five thousand, nine hundred forty-five".