64721405 has 12 divisors (see below), whose sum is σ = 90346140. Its totient is φ = 44380224.

The previous prime is 64721383. The next prime is 64721441. The reversal of 64721405 is 50412746.

It can be written as a sum of positive squares in 2 ways, for example, as 46963609 + 17757796 = 6853^2 + 4214^2 .

It is not a de Polignac number, because 64721405 - 2⁶ = 64721341 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 131840 + ... + 132329.

It is an arithmetic number, because the mean of its divisors is an integer number (7528845).

Almost surely, 2^64721405 is an apocalyptic number.

It is an amenable number.

64721405 is a deficient number, since it is larger than the sum of its proper divisors (25624735).

64721405 is a wasteful number, since it uses less digits than its factorization.

64721405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264188 (or 264181 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 64721405 is about 8044.9614666573. The cubic root of 64721405 is about 401.4973152077.

The spelling of 64721405 in words is "sixty-four million, seven hundred twenty-one thousand, four hundred five".