721521897 has 16 divisors (see below), whose sum is σ = 986673600. Its totient is φ = 468744192.

The previous prime is 721521887. The next prime is 721521919. The reversal of 721521897 is 798125127.

It is not a de Polignac number, because 721521897 - 2¹⁰ = 721520873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (721521817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51693 + ... + 64149.

It is an arithmetic number, because the mean of its divisors is an integer number (61667100).

Almost surely, 2^721521897 is an apocalyptic number.

It is an amenable number.

721521897 is a deficient number, since it is larger than the sum of its proper divisors (265151703).

721521897 is a wasteful number, since it uses less digits than its factorization.

721521897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12952.

The product of its digits is 70560, while the sum is 42.

The square root of 721521897 is about 26861.1596361736. The cubic root of 721521897 is about 896.9120082614.

The spelling of 721521897 in words is "seven hundred twenty-one million, five hundred twenty-one thousand, eight hundred ninety-seven".