64720815 has 8 divisors (see below), whose sum is σ = 103553328. Its totient is φ = 34517760.

The previous prime is 64720811. The next prime is 64720823. The reversal of 64720815 is 51802746.

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

It is not a de Polignac number, because 64720815 - 2² = 64720811 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64720811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2157346 + ... + 2157375.

It is an arithmetic number, because the mean of its divisors is an integer number (12944166).

Almost surely, 2^64720815 is an apocalyptic number.

64720815 is a deficient number, since it is larger than the sum of its proper divisors (38832513).

64720815 is a wasteful number, since it uses less digits than its factorization.

64720815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4314729.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 64720815 is about 8044.9247976597. The cubic root of 64720815 is about 401.4960951882.

The spelling of 64720815 in words is "sixty-four million, seven hundred twenty thousand, eight hundred fifteen".