64447561 has 4 divisors (see below), whose sum is σ = 68238612. Its totient is φ = 60656512.

The previous prime is 64447553. The next prime is 64447573. The reversal of 64447561 is 16574446.

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 45481536 + 18966025 = 6744^2 + 4355^2 .

It is a cyclic number.

It is not a de Polignac number, because 64447561 - 2³ = 64447553 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 64447561.

It is not an unprimeable number, because it can be changed into a prime (64447261) 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, 1895500 + ... + 1895533.

It is an arithmetic number, because the mean of its divisors is an integer number (17059653).

Almost surely, 2^64447561 is an apocalyptic number.

It is an amenable number.

64447561 is a deficient number, since it is larger than the sum of its proper divisors (3791051).

64447561 is a wasteful number, since it uses less digits than its factorization.

64447561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3791050.

The product of its digits is 80640, while the sum is 37.

The square root of 64447561 is about 8027.9238287368. The cubic root of 64447561 is about 400.9302536433.

It can be divided in two parts, 644 and 47561, that added together give a triangular number (48205 = T₃₁₀).

The spelling of 64447561 in words is "sixty-four million, four hundred forty-seven thousand, five hundred sixty-one".