721377021 has 8 divisors (see below), whose sum is σ = 975012160. Its totient is φ = 474329952.

The previous prime is 721376993. The next prime is 721377023. The reversal of 721377021 is 120773127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 721377021 - 2¹⁹ = 720852733 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 721377021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721377023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1646761 + ... + 1647198.

It is an arithmetic number, because the mean of its divisors is an integer number (121876520).

Almost surely, 2^721377021 is an apocalyptic number.

It is an amenable number.

721377021 is a deficient number, since it is larger than the sum of its proper divisors (253635139).

721377021 is a wasteful number, since it uses less digits than its factorization.

721377021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3294035.

The product of its (nonzero) digits is 4116, while the sum is 30.

The square root of 721377021 is about 26858.4627445429. The cubic root of 721377021 is about 896.8519732517.

The spelling of 721377021 in words is "seven hundred twenty-one million, three hundred seventy-seven thousand, twenty-one".