64870991 has 4 divisors (see below), whose sum is σ = 65034792. Its totient is φ = 64707192.

The previous prime is 64870969. The next prime is 64871011. The reversal of 64870991 is 19907846.

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

It is a cyclic number.

It is not a de Polignac number, because 64870991 - 2¹⁴ = 64854607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64870931) 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, 81305 + ... + 82098.

It is an arithmetic number, because the mean of its divisors is an integer number (16258698).

Almost surely, 2^64870991 is an apocalyptic number.

64870991 is a deficient number, since it is larger than the sum of its proper divisors (163801).

64870991 is a wasteful number, since it uses less digits than its factorization.

64870991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163800.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 64870991 is about 8054.2529759128. The cubic root of 64870991 is about 401.8063946493.

The spelling of 64870991 in words is "sixty-four million, eight hundred seventy thousand, nine hundred ninety-one".