64616781 has 8 divisors (see below), whose sum is σ = 86433984. Its totient is φ = 42938720.

The previous prime is 64616771. The next prime is 64616789. The reversal of 64616781 is 18761646.

It is a happy number.

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 64616781 - 2⁷ = 64616653 is a prime.

It is a super-2 number, since 2×64616781² = 8350656773603922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64616789) 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 7 ways as a sum of consecutive naturals, for example, 33696 + ... + 35561.

It is an arithmetic number, because the mean of its divisors is an integer number (10804248).

Almost surely, 2^64616781 is an apocalyptic number.

It is an amenable number.

64616781 is a deficient number, since it is larger than the sum of its proper divisors (21817203).

64616781 is a wasteful number, since it uses less digits than its factorization.

64616781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69571.

The product of its digits is 48384, while the sum is 39.

The square root of 64616781 is about 8038.4563816693. The cubic root of 64616781 is about 401.2808545678.

The spelling of 64616781 in words is "sixty-four million, six hundred sixteen thousand, seven hundred eighty-one".