64640261 has 12 divisors (see below), whose sum is σ = 79152480. Its totient is φ = 52489080.

The previous prime is 64640243. The next prime is 64640263. The reversal of 64640261 is 16204646.

64640261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 64640261 - 2¹⁴ = 64623877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64640263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33785 + ... + 35646.

It is an arithmetic number, because the mean of its divisors is an integer number (6596040).

Almost surely, 2^64640261 is an apocalyptic number.

It is an amenable number.

64640261 is a deficient number, since it is larger than the sum of its proper divisors (14512219).

64640261 is a wasteful number, since it uses less digits than its factorization.

64640261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69464 (or 69457 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 64640261 is about 8039.9167284245. The cubic root of 64640261 is about 401.3294535711.

The spelling of 64640261 in words is "sixty-four million, six hundred forty thousand, two hundred sixty-one".