21686292 has 96 divisors (see below), whose sum is σ = 59328640. Its totient is φ = 6928416.

The previous prime is 21686281. The next prime is 21686299. The reversal of 21686292 is 29268612.

It is a happy number.

21686292 is a `hidden beast` number, since 21 + 6 + 8 + 629 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21686299) 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, 323643 + ... + 323709.

Almost surely, 2^21686292 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21686292, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29664320).

21686292 is an abundant number, since it is smaller than the sum of its proper divisors (37642348).

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

21686292 is an equidigital number, since it uses as much as digits as its factorization.

21686292 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 109 counting only the distinct ones).

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

The square root of 21686292 is about 4656.8543030677. The cubic root of 21686292 is about 278.8657001919.

The spelling of 21686292 in words is "twenty-one million, six hundred eighty-six thousand, two hundred ninety-two".