64885771781 has 4 divisors (see below), whose sum is σ = 64899751392. Its totient is φ = 64871792172.

The previous prime is 64885771771. The next prime is 64885771789. The reversal of 64885771781 is 18717758846.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 64885771781 - 2¹⁰ = 64885770757 is a prime.

It is a super-2 number, since 2×64885771781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64885771789) 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, 6982841 + ... + 6992126.

It is an arithmetic number, because the mean of its divisors is an integer number (16224937848).

Almost surely, 2^64885771781 is an apocalyptic number.

It is an amenable number.

64885771781 is a deficient number, since it is larger than the sum of its proper divisors (13979611).

64885771781 is a wasteful number, since it uses less digits than its factorization.

64885771781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13979610.

The product of its digits is 21073920, while the sum is 62.

The spelling of 64885771781 in words is "sixty-four billion, eight hundred eighty-five million, seven hundred seventy-one thousand, seven hundred eighty-one".