21661444252 has 48 divisors (see below), whose sum is σ = 45645530112. Its totient is φ = 8793607680.

The previous prime is 21661444241. The next prime is 21661444253. The reversal of 21661444252 is 25244416612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661444253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 96949 + ... + 229612.

It is an arithmetic number, because the mean of its divisors is an integer number (950948544).

Almost surely, 2^21661444252 is an apocalyptic number.

It is an amenable number.

21661444252 is an abundant number, since it is smaller than the sum of its proper divisors (23984085860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661444252 is a wasteful number, since it uses less digits than its factorization.

21661444252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 326698 (or 326696 counting only the distinct ones).

The product of its digits is 92160, while the sum is 37.

The spelling of 21661444252 in words is "twenty-one billion, six hundred sixty-one million, four hundred forty-four thousand, two hundred fifty-two".