21661892 has 24 divisors (see below), whose sum is σ = 43647744. Its totient is φ = 9214272.

The previous prime is 21661891. The next prime is 21661903. The reversal of 21661892 is 29816612.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661891) 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, 1013 + ... + 6659.

It is an arithmetic number, because the mean of its divisors is an integer number (1818656).

Almost surely, 2^21661892 is an apocalyptic number.

It is an amenable number.

21661892 is an abundant number, since it is smaller than the sum of its proper divisors (21985852).

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

21661892 is a wasteful number, since it uses less digits than its factorization.

21661892 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5795 (or 5793 counting only the distinct ones).

The product of its digits is 10368, while the sum is 35.

The square root of 21661892 is about 4654.2337715246. The cubic root of 21661892 is about 278.7610737824.

The spelling of 21661892 in words is "twenty-one million, six hundred sixty-one thousand, eight hundred ninety-two".