64721399 has 12 divisors (see below), whose sum is σ = 67614312. Its totient is φ = 61906320.

The previous prime is 64721383. The next prime is 64721441. The reversal of 64721399 is 99312746.

It is not a de Polignac number, because 64721399 - 2⁴ = 64721383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64721309) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 186344 + ... + 186690.

It is an arithmetic number, because the mean of its divisors is an integer number (5634526).

Almost surely, 2^64721399 is an apocalyptic number.

64721399 is a deficient number, since it is larger than the sum of its proper divisors (2892913).

64721399 is an equidigital number, since it uses as much as digits as its factorization.

64721399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 455 counting only the distinct ones).

The product of its digits is 81648, while the sum is 41.

The square root of 64721399 is about 8044.9610937530. The cubic root of 64721399 is about 401.4973028008.

The spelling of 64721399 in words is "sixty-four million, seven hundred twenty-one thousand, three hundred ninety-nine".