64855001781 has 16 divisors (see below), whose sum is σ = 96112995520. Its totient is φ = 43222487760.

The previous prime is 64855001777. The next prime is 64855001803. The reversal of 64855001781 is 18710055846.

64855001781 is a `hidden beast` number, since 6 + 4 + 8 + 550 + 0 + 17 + 81 = 666.

It is not a de Polignac number, because 64855001781 - 2² = 64855001777 is a prime.

It is a super-2 number, since 2×64855001781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64855001381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 309715 + ... + 475008.

It is an arithmetic number, because the mean of its divisors is an integer number (6007062220).

Almost surely, 2^64855001781 is an apocalyptic number.

It is an amenable number.

64855001781 is a deficient number, since it is larger than the sum of its proper divisors (31257993739).

64855001781 is a wasteful number, since it uses less digits than its factorization.

64855001781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 787793 (or 787787 counting only the distinct ones).

The product of its (nonzero) digits is 268800, while the sum is 45.

The spelling of 64855001781 in words is "sixty-four billion, eight hundred fifty-five million, one thousand, seven hundred eighty-one".