20261312656 has 60 divisors (see below), whose sum is σ = 42929746740. Its totient is φ = 9258662400.

The previous prime is 20261312647. The next prime is 20261312681. The reversal of 20261312656 is 65621316202.

It can be written as a sum of positive squares in 6 ways, for example, as 661312656 + 19600000000 = 25716^2 + 140000^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 236010 + ... + 310198.

It is an arithmetic number, because the mean of its divisors is an integer number (715495779).

Almost surely, 2^20261312656 is an apocalyptic number.

20261312656 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20261312656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21464873370).

20261312656 is an abundant number, since it is smaller than the sum of its proper divisors (22668434084).

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

20261312656 is a wasteful number, since it uses less digits than its factorization.

20261312656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74324 (or 74305 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

Adding to 20261312656 its reverse (65621316202), we get a palindrome (85882628858).

The spelling of 20261312656 in words is "twenty billion, two hundred sixty-one million, three hundred twelve thousand, six hundred fifty-six".