64919721 has 8 divisors (see below), whose sum is σ = 86610240. Its totient is φ = 43254512.

The previous prime is 64919707. The next prime is 64919741. The reversal of 64919721 is 12791946.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 64919721 - 2¹⁰ = 64918697 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 64919721.

It is not an unprimeable number, because it can be changed into a prime (64919741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 811 + ... + 11423.

It is an arithmetic number, because the mean of its divisors is an integer number (10826280).

Almost surely, 2^64919721 is an apocalyptic number.

It is an amenable number.

64919721 is a deficient number, since it is larger than the sum of its proper divisors (21690519).

64919721 is a wasteful number, since it uses less digits than its factorization.

64919721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12655.

The product of its digits is 27216, while the sum is 39.

The square root of 64919721 is about 8057.2775178717. The cubic root of 64919721 is about 401.9069795416.

The spelling of 64919721 in words is "sixty-four million, nine hundred nineteen thousand, seven hundred twenty-one".