64551561 has 4 divisors (see below), whose sum is σ = 86068752. Its totient is φ = 43034372.

The previous prime is 64551551. The next prime is 64551577. The reversal of 64551561 is 16515546.

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 64551561 - 2⁶ = 64551497 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (64551511) 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, 10758591 + ... + 10758596.

It is an arithmetic number, because the mean of its divisors is an integer number (21517188).

Almost surely, 2^64551561 is an apocalyptic number.

It is an amenable number.

64551561 is a deficient number, since it is larger than the sum of its proper divisors (21517191).

64551561 is a wasteful number, since it uses less digits than its factorization.

64551561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21517190.

The product of its digits is 18000, while the sum is 33.

The square root of 64551561 is about 8034.3986084834. The cubic root of 64551561 is about 401.1458001379.

The spelling of 64551561 in words is "sixty-four million, five hundred fifty-one thousand, five hundred sixty-one".