21857526461 has 4 divisors (see below), whose sum is σ = 22611234300. Its totient is φ = 21103818624.

The previous prime is 21857526421. The next prime is 21857526463. The reversal of 21857526461 is 16462575812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6174973561 + 15682552900 = 78581^2 + 125230^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21857526461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857526463) 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, 376853876 + ... + 376853933.

It is an arithmetic number, because the mean of its divisors is an integer number (5652808575).

Almost surely, 2^21857526461 is an apocalyptic number.

It is an amenable number.

21857526461 is a deficient number, since it is larger than the sum of its proper divisors (753707839).

21857526461 is an equidigital number, since it uses as much as digits as its factorization.

21857526461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 753707838.

The product of its digits is 806400, while the sum is 47.

The spelling of 21857526461 in words is "twenty-one billion, eight hundred fifty-seven million, five hundred twenty-six thousand, four hundred sixty-one".