64775561 has 4 divisors (see below), whose sum is σ = 64996932. Its totient is φ = 64554192.

The previous prime is 64775551. The next prime is 64775591. The reversal of 64775561 is 16557746.

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

It can be written as a sum of positive squares in 2 ways, for example, as 46840336 + 17935225 = 6844^2 + 4235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64775561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64775551) 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, 110246 + ... + 110831.

It is an arithmetic number, because the mean of its divisors is an integer number (16249233).

Almost surely, 2^64775561 is an apocalyptic number.

It is an amenable number.

64775561 is a deficient number, since it is larger than the sum of its proper divisors (221371).

64775561 is a wasteful number, since it uses less digits than its factorization.

64775561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221370.

The product of its digits is 176400, while the sum is 41.

The square root of 64775561 is about 8048.3265962559. The cubic root of 64775561 is about 401.6092690338.

The spelling of 64775561 in words is "sixty-four million, seven hundred seventy-five thousand, five hundred sixty-one".