64023721 has 4 divisors (see below), whose sum is σ = 64124244. Its totient is φ = 63923200.

The previous prime is 64023703. The next prime is 64023731. The reversal of 64023721 is 12732046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12732046 = 2 ⋅6366023.

It can be written as a sum of positive squares in 2 ways, for example, as 62094400 + 1929321 = 7880^2 + 1389^2 .

It is a cyclic number.

It is not a de Polignac number, because 64023721 - 2¹³ = 64015529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64023731) 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, 49300 + ... + 50581.

It is an arithmetic number, because the mean of its divisors is an integer number (16031061).

Almost surely, 2^64023721 is an apocalyptic number.

It is an amenable number.

64023721 is a deficient number, since it is larger than the sum of its proper divisors (100523).

64023721 is an equidigital number, since it uses as much as digits as its factorization.

64023721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100522.

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 64023721 is about 8001.4824251510. The cubic root of 64023721 is about 400.0494126457.

Adding to 64023721 its reverse (12732046), we get a palindrome (76755767).

The spelling of 64023721 in words is "sixty-four million, twenty-three thousand, seven hundred twenty-one".