64707821 has 4 divisors (see below), whose sum is σ = 64724352. Its totient is φ = 64691292.

The previous prime is 64707791. The next prime is 64707829. The reversal of 64707821 is 12870746.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-64707821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64707829) 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, 1286 + ... + 11448.

It is an arithmetic number, because the mean of its divisors is an integer number (16181088).

Almost surely, 2^64707821 is an apocalyptic number.

It is an amenable number.

64707821 is a deficient number, since it is larger than the sum of its proper divisors (16531).

64707821 is a wasteful number, since it uses less digits than its factorization.

64707821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16530.

The product of its (nonzero) digits is 18816, while the sum is 35.

The square root of 64707821 is about 8044.1171672223. The cubic root of 64707821 is about 401.4692239287.

The spelling of 64707821 in words is "sixty-four million, seven hundred seven thousand, eight hundred twenty-one".