721145845 has 16 divisors (see below), whose sum is σ = 995644800. Its totient is φ = 491177664.

The previous prime is 721145837. The next prime is 721145861. The reversal of 721145845 is 548541127.

It is a cyclic number.

It is not a de Polignac number, because 721145845 - 2³ = 721145837 is a prime.

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, 63927 + ... + 74356.

It is an arithmetic number, because the mean of its divisors is an integer number (62227800).

Almost surely, 2^721145845 is an apocalyptic number.

It is an amenable number.

721145845 is a deficient number, since it is larger than the sum of its proper divisors (274498955).

721145845 is a wasteful number, since it uses less digits than its factorization.

721145845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138444.

The product of its digits is 44800, while the sum is 37.

The square root of 721145845 is about 26854.1588026883. The cubic root of 721145845 is about 896.7561598296.

The spelling of 721145845 in words is "seven hundred twenty-one million, one hundred forty-five thousand, eight hundred forty-five".