21633650661 has 32 divisors (see below), whose sum is σ = 34739509248. Its totient is φ = 11707502400.

The previous prime is 21633650651. The next prime is 21633650663. The reversal of 21633650661 is 16605633612.

It is a happy number.

It is not a de Polignac number, because 21633650661 - 2¹⁵ = 21633617893 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21633650663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 172951 + ... + 270516.

It is an arithmetic number, because the mean of its divisors is an integer number (1085609664).

Almost surely, 2^21633650661 is an apocalyptic number.

21633650661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21633650661 is a deficient number, since it is larger than the sum of its proper divisors (13105858587).

21633650661 is a wasteful number, since it uses less digits than its factorization.

21633650661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443601.

The product of its (nonzero) digits is 116640, while the sum is 39.

The spelling of 21633650661 in words is "twenty-one billion, six hundred thirty-three million, six hundred fifty thousand, six hundred sixty-one".