64431661 has 4 divisors (see below), whose sum is σ = 73636192. Its totient is φ = 55227132.

The previous prime is 64431659. The next prime is 64431721. The reversal of 64431661 is 16613446.

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 64431661 - 2¹ = 64431659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64431611) 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, 4602255 + ... + 4602268.

It is an arithmetic number, because the mean of its divisors is an integer number (18409048).

Almost surely, 2^64431661 is an apocalyptic number.

It is an amenable number.

64431661 is a deficient number, since it is larger than the sum of its proper divisors (9204531).

64431661 is an equidigital number, since it uses as much as digits as its factorization.

64431661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9204530.

The product of its digits is 10368, while the sum is 31.

The square root of 64431661 is about 8026.9334742478. The cubic root of 64431661 is about 400.8972794689.

The spelling of 64431661 in words is "sixty-four million, four hundred thirty-one thousand, six hundred sixty-one".