64823921 has 4 divisors (see below), whose sum is σ = 65465844. Its totient is φ = 64182000.

The previous prime is 64823893. The next prime is 64823981. The reversal of 64823921 is 12932846.

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 59367025 + 5456896 = 7705^2 + 2336^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64823921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64823981) 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, 320810 + ... + 321011.

It is an arithmetic number, because the mean of its divisors is an integer number (16366461).

Almost surely, 2^64823921 is an apocalyptic number.

It is an amenable number.

64823921 is a deficient number, since it is larger than the sum of its proper divisors (641923).

64823921 is a wasteful number, since it uses less digits than its factorization.

64823921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641922.

The product of its digits is 20736, while the sum is 35.

The square root of 64823921 is about 8051.3303869609. The cubic root of 64823921 is about 401.7091883689.

The spelling of 64823921 in words is "sixty-four million, eight hundred twenty-three thousand, nine hundred twenty-one".