21461609237 has 4 divisors (see below), whose sum is σ = 21464093580. Its totient is φ = 21459124896.

The previous prime is 21461609171. The next prime is 21461609243. The reversal of 21461609237 is 73290616412.

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 17180393476 + 4281215761 = 131074^2 + 65431^2 .

It is a cyclic number.

It is not a de Polignac number, because 21461609237 - 2²⁶ = 21394500373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21461609194 and 21461609203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21461609737) 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, 1229168 + ... + 1246505.

It is an arithmetic number, because the mean of its divisors is an integer number (5366023395).

Almost surely, 2^21461609237 is an apocalyptic number.

It is an amenable number.

21461609237 is a deficient number, since it is larger than the sum of its proper divisors (2484343).

21461609237 is an equidigital number, since it uses as much as digits as its factorization.

21461609237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2484342.

The product of its (nonzero) digits is 108864, while the sum is 41.

The spelling of 21461609237 in words is "twenty-one billion, four hundred sixty-one million, six hundred nine thousand, two hundred thirty-seven".