21126990 has 16 divisors (see below), whose sum is σ = 50704848. Its totient is φ = 5633856.

The previous prime is 21126983. The next prime is 21127009. The reversal of 21126990 is 9962112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 704233 = 21126990 / (2 + 1 + 1 + 2 + 6 + 9 + 9 + 0).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 352087 + ... + 352146.

It is an arithmetic number, because the mean of its divisors is an integer number (3169053).

Almost surely, 2^21126990 is an apocalyptic number.

21126990 is an abundant number, since it is smaller than the sum of its proper divisors (29577858).

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

21126990 is a wasteful number, since it uses less digits than its factorization.

21126990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 704243.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 21126990 is about 4596.4105560753. The cubic root of 21126990 is about 276.4474206969.

The spelling of 21126990 in words is "twenty-one million, one hundred twenty-six thousand, nine hundred ninety".