64720557 has 12 divisors (see below), whose sum is σ = 101984064. Its totient is φ = 39224520.

The previous prime is 64720553. The next prime is 64720561. The reversal of 64720557 is 75502746.

64720557 is a `hidden beast` number, since 647 + 2 + 0 + 5 + 5 + 7 = 666.

It is an interprime number because it is at equal distance from previous prime (64720553) and next prime (64720561).

It is not a de Polignac number, because 64720557 - 2² = 64720553 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64720553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 326773 + ... + 326970.

It is an arithmetic number, because the mean of its divisors is an integer number (8498672).

Almost surely, 2^64720557 is an apocalyptic number.

It is an amenable number.

64720557 is a deficient number, since it is larger than the sum of its proper divisors (37263507).

64720557 is a wasteful number, since it uses less digits than its factorization.

64720557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653760 (or 653757 counting only the distinct ones).

The product of its (nonzero) digits is 58800, while the sum is 36.

The square root of 64720557 is about 8044.9087626896. The cubic root of 64720557 is about 401.4955616858.

The spelling of 64720557 in words is "sixty-four million, seven hundred twenty thousand, five hundred fifty-seven".