721428615 has 48 divisors (see below), whose sum is σ = 1282065408. Its totient is φ = 375108288.

The previous prime is 721428607. The next prime is 721428629. The reversal of 721428615 is 516824127.

721428615 is a `hidden beast` number, since 7 + 2 + 14 + 28 + 615 = 666.

It is not a de Polignac number, because 721428615 - 2³ = 721428607 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721428615.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 733414 + ... + 734396.

It is an arithmetic number, because the mean of its divisors is an integer number (26709696).

Almost surely, 2^721428615 is an apocalyptic number.

721428615 is a deficient number, since it is larger than the sum of its proper divisors (560636793).

721428615 is a wasteful number, since it uses less digits than its factorization.

721428615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1388 (or 1385 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 721428615 is about 26859.4232067630. The cubic root of 721428615 is about 896.8733541553.

It can be divided in two parts, 7214286 and 15, that added together give a triangular number (7214301 = T₃₇₉₈).

The spelling of 721428615 in words is "seven hundred twenty-one million, four hundred twenty-eight thousand, six hundred fifteen".