21582181661 has 8 divisors (see below), whose sum is σ = 21677779200. Its totient is φ = 21486634560.

The previous prime is 21582181633. The next prime is 21582181697. The reversal of 21582181661 is 16618128512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21582181661 - 2¹⁴ = 21582165277 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 (21582181861) 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, 1035380 + ... + 1056018.

It is an arithmetic number, because the mean of its divisors is an integer number (2709722400).

Almost surely, 2^21582181661 is an apocalyptic number.

It is an amenable number.

21582181661 is a deficient number, since it is larger than the sum of its proper divisors (95597539).

21582181661 is a wasteful number, since it uses less digits than its factorization.

21582181661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25219.

The product of its digits is 46080, while the sum is 41.

The spelling of 21582181661 in words is "twenty-one billion, five hundred eighty-two million, one hundred eighty-one thousand, six hundred sixty-one".