721428556 has 24 divisors (see below), whose sum is σ = 1332254000. Its totient is φ = 340879104.

The previous prime is 721428529. The next prime is 721428569. The reversal of 721428556 is 655824127.

It is a super-2 number, since 2×721428556² = 1040918322824490272, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19480 + ... + 42688.

Almost surely, 2^721428556 is an apocalyptic number.

721428556 is a gapful number since it is divisible by the number (76) formed by its first and last digit.

It is an amenable number.

721428556 is a deficient number, since it is larger than the sum of its proper divisors (610825444).

721428556 is a wasteful number, since it uses less digits than its factorization.

721428556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23641 (or 23639 counting only the distinct ones).

The product of its digits is 134400, while the sum is 40.

The square root of 721428556 is about 26859.4221084520. The cubic root of 721428556 is about 896.8733297059.

The spelling of 721428556 in words is "seven hundred twenty-one million, four hundred twenty-eight thousand, five hundred fifty-six".