21069990 has 64 divisors (see below), whose sum is σ = 57009600. Its totient is φ = 5536512.

The previous prime is 21069977. The next prime is 21070009. The reversal of 21069990 is 9996012.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19176 + ... + 20244.

It is an arithmetic number, because the mean of its divisors is an integer number (890775).

Almost surely, 2^21069990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21069990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28504800).

21069990 is an abundant number, since it is smaller than the sum of its proper divisors (35939610).

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

21069990 is a wasteful number, since it uses less digits than its factorization.

21069990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1158 (or 1152 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 21069990 is about 4590.2058777358. The cubic root of 21069990 is about 276.1985810948.

The spelling of 21069990 in words is "twenty-one million, sixty-nine thousand, nine hundred ninety".