64638723 has 4 divisors (see below), whose sum is σ = 86184968. Its totient is φ = 43092480.

The previous prime is 64638713. The next prime is 64638731. The reversal of 64638723 is 32783646.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 64638723 - 2⁶ = 64638659 is a prime.

It is a super-2 number, since 2×64638723² = 8356329022141458, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64638713) 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, 10773118 + ... + 10773123.

It is an arithmetic number, because the mean of its divisors is an integer number (21546242).

Almost surely, 2^64638723 is an apocalyptic number.

64638723 is a deficient number, since it is larger than the sum of its proper divisors (21546245).

64638723 is a wasteful number, since it uses less digits than its factorization.

64638723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21546244.

The product of its digits is 145152, while the sum is 39.

The square root of 64638723 is about 8039.8210800987. The cubic root of 64638723 is about 401.3262705724.

The spelling of 64638723 in words is "sixty-four million, six hundred thirty-eight thousand, seven hundred twenty-three".