64438591 has 4 divisors (see below), whose sum is σ = 73644112. Its totient is φ = 55233072.

The previous prime is 64438573. The next prime is 64438603. The reversal of 64438591 is 19583446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19583446 = 2 ⋅9791723.

It is a cyclic number.

It is not a de Polignac number, because 64438591 - 2⁹ = 64438079 is a prime.

It is a super-4 number, since 4×64438591⁴ (a number of 32 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64438501) 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, 4602750 + ... + 4602763.

It is an arithmetic number, because the mean of its divisors is an integer number (18411028).

Almost surely, 2^64438591 is an apocalyptic number.

64438591 is a deficient number, since it is larger than the sum of its proper divisors (9205521).

64438591 is an equidigital number, since it uses as much as digits as its factorization.

64438591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9205520.

The product of its digits is 103680, while the sum is 40.

The square root of 64438591 is about 8027.3651343389. The cubic root of 64438591 is about 400.9116518985.

It can be divided in two parts, 644385 and 91, that multiplied together give a triangular number (58639035 = T₁₀₈₂₉).

The spelling of 64438591 in words is "sixty-four million, four hundred thirty-eight thousand, five hundred ninety-one".