721428618 has 16 divisors (see below), whose sum is σ = 1443610080. Its totient is φ = 240350736.

The previous prime is 721428607. The next prime is 721428629. The reversal of 721428618 is 816824127.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (721428607) and next prime (721428629).

It is a super-3 number, since 3×721428618³ (a number of 28 digits) contains 333 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, 18505 + ... + 42252.

It is an arithmetic number, because the mean of its divisors is an integer number (90225630).

Almost surely, 2^721428618 is an apocalyptic number.

721428618 is an abundant number, since it is smaller than the sum of its proper divisors (722181462).

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

721428618 is a wasteful number, since it uses less digits than its factorization.

721428618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62741.

The product of its digits is 43008, while the sum is 39.

The square root of 721428618 is about 26859.4232626093. The cubic root of 721428618 is about 896.8733553985.

The spelling of 721428618 in words is "seven hundred twenty-one million, four hundred twenty-eight thousand, six hundred eighteen".