21661462161 has 24 divisors (see below), whose sum is σ = 31402785024. Its totient is φ = 14388423840.

The previous prime is 21661462139. The next prime is 21661462177. The reversal of 21661462161 is 16126416612.

21661462161 is a `hidden beast` number, since 2 + 16 + 6 + 14 + 621 + 6 + 1 = 666.

It is not a de Polignac number, because 21661462161 - 2⁵ = 21661462129 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661462181) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8090355 + ... + 8093031.

It is an arithmetic number, because the mean of its divisors is an integer number (1308449376).

Almost surely, 2^21661462161 is an apocalyptic number.

It is an amenable number.

21661462161 is a deficient number, since it is larger than the sum of its proper divisors (9741322863).

21661462161 is a wasteful number, since it uses less digits than its factorization.

21661462161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5621 (or 5618 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

Adding to 21661462161 its reverse (16126416612), we get a palindrome (37787878773).

The spelling of 21661462161 in words is "twenty-one billion, six hundred sixty-one million, four hundred sixty-two thousand, one hundred sixty-one".