715521421 has 4 divisors (see below), whose sum is σ = 746631072. Its totient is φ = 684411772.

The previous prime is 715521413. The next prime is 715521427. The reversal of 715521421 is 124125517.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 715521421 - 2³ = 715521413 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 715521421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (715521427) 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, 15554791 + ... + 15554836.

It is an arithmetic number, because the mean of its divisors is an integer number (186657768).

Almost surely, 2^715521421 is an apocalyptic number.

It is an amenable number.

715521421 is a deficient number, since it is larger than the sum of its proper divisors (31109651).

715521421 is a wasteful number, since it uses less digits than its factorization.

715521421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31109650.

The product of its digits is 2800, while the sum is 28.

The square root of 715521421 is about 26749.2321572041. The cubic root of 715521421 is about 894.4187193364.

Adding to 715521421 its reverse (124125517), we get a palindrome (839646938).

The spelling of 715521421 in words is "seven hundred fifteen million, five hundred twenty-one thousand, four hundred twenty-one".