64187561 has 4 divisors (see below), whose sum is σ = 64618500. Its totient is φ = 63756624.

The previous prime is 64187471. The next prime is 64187569. The reversal of 64187561 is 16578146.

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 39137536 + 25050025 = 6256^2 + 5005^2 .

It is a cyclic number.

It is not a de Polignac number, because 64187561 - 2¹⁸ = 63925417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64187569) 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, 215246 + ... + 215543.

It is an arithmetic number, because the mean of its divisors is an integer number (16154625).

Almost surely, 2^64187561 is an apocalyptic number.

It is an amenable number.

64187561 is a deficient number, since it is larger than the sum of its proper divisors (430939).

64187561 is a wasteful number, since it uses less digits than its factorization.

64187561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 430938.

The product of its digits is 40320, while the sum is 38.

The square root of 64187561 is about 8011.7139864077. The cubic root of 64187561 is about 400.3903709856.

The spelling of 64187561 in words is "sixty-four million, one hundred eighty-seven thousand, five hundred sixty-one".