21685650 has 96 divisors (see below), whose sum is σ = 64757760. Its totient is φ = 4691520.

The previous prime is 21685621. The next prime is 21685661. The reversal of 21685650 is 5658612.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19407 + ... + 20493.

It is an arithmetic number, because the mean of its divisors is an integer number (674560).

Almost surely, 2^21685650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21685650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32378880).

21685650 is an abundant number, since it is smaller than the sum of its proper divisors (43072110).

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

21685650 is a wasteful number, since it uses less digits than its factorization.

21685650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1128 (or 1123 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 21685650 is about 4656.7853719062. The cubic root of 21685650 is about 278.8629483223.

The spelling of 21685650 in words is "twenty-one million, six hundred eighty-five thousand, six hundred fifty".