64991385 has 24 divisors (see below), whose sum is σ = 113657544. Its totient is φ = 34352640.

The previous prime is 64991383. The next prime is 64991387. The reversal of 64991385 is 58319946.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (64991383) and next prime (64991387).

It can be written as a sum of positive squares in 4 ways, for example, as 927369 + 64064016 = 963^2 + 8004^2 .

It is not a de Polignac number, because 64991385 - 2¹ = 64991383 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 64991385.

It is not an unprimeable number, because it can be changed into a prime (64991383) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1306 + ... + 11475.

It is an arithmetic number, because the mean of its divisors is an integer number (4735731).

Almost surely, 2^64991385 is an apocalyptic number.

It is an amenable number.

64991385 is a deficient number, since it is larger than the sum of its proper divisors (48666159).

64991385 is a wasteful number, since it uses less digits than its factorization.

64991385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12905 (or 12902 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 64991385 is about 8061.7234509750. The cubic root of 64991385 is about 402.0548117139.

The spelling of 64991385 in words is "sixty-four million, nine hundred ninety-one thousand, three hundred eighty-five".