640481281 has 8 divisors (see below), whose sum is σ = 703735200. Its totient is φ = 578065440.

The previous prime is 640481251. The next prime is 640481287. The reversal of 640481281 is 182184046.

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 640481281 - 2⁵ = 640481249 is a prime.

It is a super-2 number, since 2×640481281² = 820432542622801922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640481287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207916 + ... + 210973.

It is an arithmetic number, because the mean of its divisors is an integer number (87966900).

Almost surely, 2^640481281 is an apocalyptic number.

It is an amenable number.

640481281 is a deficient number, since it is larger than the sum of its proper divisors (63253919).

640481281 is a wasteful number, since it uses less digits than its factorization.

640481281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 419039.

The product of its (nonzero) digits is 12288, while the sum is 34.

The square root of 640481281 is about 25307.7316446970. The cubic root of 640481281 is about 861.9898403204.

The spelling of 640481281 in words is "six hundred forty million, four hundred eighty-one thousand, two hundred eighty-one".