64216561 has 4 divisors (see below), whose sum is σ = 67596400. Its totient is φ = 60836724.

The previous prime is 64216553. The next prime is 64216573. The reversal of 64216561 is 16561246.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 64216561 - 2³ = 64216553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64216511) 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, 1689891 + ... + 1689928.

It is an arithmetic number, because the mean of its divisors is an integer number (16899100).

Almost surely, 2^64216561 is an apocalyptic number.

It is an amenable number.

64216561 is a deficient number, since it is larger than the sum of its proper divisors (3379839).

64216561 is a wasteful number, since it uses less digits than its factorization.

64216561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3379838.

The product of its digits is 8640, while the sum is 31.

The square root of 64216561 is about 8013.5236319612. The cubic root of 64216561 is about 400.4506608214.

The spelling of 64216561 in words is "sixty-four million, two hundred sixteen thousand, five hundred sixty-one".