64878469981 has 4 divisors (see below), whose sum is σ = 69869121532. Its totient is φ = 59887818432.

The previous prime is 64878469969. The next prime is 64878469993. The reversal of 64878469981 is 18996487846.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (64878469969) and next prime (64878469993).

It can be written as a sum of positive squares in 2 ways, for example, as 15978224025 + 48900245956 = 126405^2 + 221134^2 .

It is not a de Polignac number, because 64878469981 - 2¹⁵ = 64878437213 is a prime.

It is a super-2 number, since 2×64878469981² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 64878469981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64878469781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2495325756 + ... + 2495325781.

It is an arithmetic number, because the mean of its divisors is an integer number (17467280383).

Almost surely, 2^64878469981 is an apocalyptic number.

It is an amenable number.

64878469981 is a deficient number, since it is larger than the sum of its proper divisors (4990651551).

64878469981 is a wasteful number, since it uses less digits than its factorization.

64878469981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4990651550.

The product of its digits is 167215104, while the sum is 70.

The spelling of 64878469981 in words is "sixty-four billion, eight hundred seventy-eight million, four hundred sixty-nine thousand, nine hundred eighty-one".