721428751 has 4 divisors (see below), whose sum is σ = 722875000. Its totient is φ = 719982504.

The previous prime is 721428703. The next prime is 721428791. The reversal of 721428751 is 157824127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 157824127 = 19 ⋅8306533.

It is a cyclic number.

It is not a de Polignac number, because 721428751 - 2²⁹ = 184557839 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721428751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721428791) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 722376 + ... + 723373.

It is an arithmetic number, because the mean of its divisors is an integer number (180718750).

Almost surely, 2^721428751 is an apocalyptic number.

721428751 is a deficient number, since it is larger than the sum of its proper divisors (1446249).

721428751 is a wasteful number, since it uses less digits than its factorization.

721428751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1446248.

The product of its digits is 31360, while the sum is 37.

The square root of 721428751 is about 26859.4257384628. The cubic root of 721428751 is about 896.8734105133.

The spelling of 721428751 in words is "seven hundred twenty-one million, four hundred twenty-eight thousand, seven hundred fifty-one".