21612542461 has 4 divisors (see below), whose sum is σ = 21978856800. Its totient is φ = 21246228124.

The previous prime is 21612542449. The next prime is 21612542467. The reversal of 21612542461 is 16424521612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21612542461 - 2⁷ = 21612542333 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 (21612542467) 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, 183157081 + ... + 183157198.

It is an arithmetic number, because the mean of its divisors is an integer number (5494714200).

Almost surely, 2^21612542461 is an apocalyptic number.

It is an amenable number.

21612542461 is a deficient number, since it is larger than the sum of its proper divisors (366314339).

21612542461 is an equidigital number, since it uses as much as digits as its factorization.

21612542461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366314338.

The product of its digits is 23040, while the sum is 34.

The spelling of 21612542461 in words is "twenty-one billion, six hundred twelve million, five hundred forty-two thousand, four hundred sixty-one".