64665251 has 12 divisors (see below), whose sum is σ = 76349448. Its totient is φ = 54597312.

The previous prime is 64665221. The next prime is 64665257. The reversal of 64665251 is 15256646.

It is not a de Polignac number, because 64665251 - 2⁶ = 64665187 is a prime.

It is not an unprimeable number, because it can be changed into a prime (64665257) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6566 + ... + 13131.

It is an arithmetic number, because the mean of its divisors is an integer number (6362454).

Almost surely, 2^64665251 is an apocalyptic number.

64665251 is the 6566-th pentagonal number.

64665251 is a deficient number, since it is larger than the sum of its proper divisors (11684197).

64665251 is a wasteful number, since it uses less digits than its factorization.

64665251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19778 (or 19771 counting only the distinct ones).

The product of its digits is 43200, while the sum is 35.

The square root of 64665251 is about 8041.4706988212. The cubic root of 64665251 is about 401.3811650521.

The spelling of 64665251 in words is "sixty-four million, six hundred sixty-five thousand, two hundred fifty-one".