64378721 has 8 divisors (see below), whose sum is σ = 70334784. Its totient is φ = 58439920.

The previous prime is 64378709. The next prime is 64378747. The reversal of 64378721 is 12787346.

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

It is not a de Polignac number, because 64378721 - 2²² = 60184417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64378621) 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, 4235 + ... + 12111.

It is an arithmetic number, because the mean of its divisors is an integer number (8791848).

Almost surely, 2^64378721 is an apocalyptic number.

It is an amenable number.

64378721 is a deficient number, since it is larger than the sum of its proper divisors (5956063).

64378721 is a wasteful number, since it uses less digits than its factorization.

64378721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8631.

The product of its digits is 56448, while the sum is 38.

The square root of 64378721 is about 8023.6351487340. The cubic root of 64378721 is about 400.7874508689.

The spelling of 64378721 in words is "sixty-four million, three hundred seventy-eight thousand, seven hundred twenty-one".