2561610640 has 40 divisors (see below), whose sum is σ = 6116717880. Its totient is φ = 996950016.

The previous prime is 2561610613. The next prime is 2561610641. The reversal of 2561610640 is 460161652.

It can be written as a sum of positive squares in 4 ways, for example, as 1501717504 + 1059893136 = 38752^2 + 32556^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×2561610640² = 13123698141922419200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2561610641) 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, 429745 + ... + 435664.

It is an arithmetic number, because the mean of its divisors is an integer number (152917947).

Almost surely, 2^2561610640 is an apocalyptic number.

2561610640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2561610640 is an abundant number, since it is smaller than the sum of its proper divisors (3555107240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2561610640 is a wasteful number, since it uses less digits than its factorization.

2561610640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 865459 (or 865453 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 2561610640 is about 50612.3565940176. The cubic root of 2561610640 is about 1368.2675884104.

The spelling of 2561610640 in words is "two billion, five hundred sixty-one million, six hundred ten thousand, six hundred forty".