21093090 has 64 divisors (see below), whose sum is σ = 54587520. Its totient is φ = 5196800.

The previous prime is 21093053. The next prime is 21093103. The reversal of 21093090 is 9039012.

It is a happy number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21093090.

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, 29740 + ... + 30440.

It is an arithmetic number, because the mean of its divisors is an integer number (852930).

Almost surely, 2^21093090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21093090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27293760).

21093090 is an abundant number, since it is smaller than the sum of its proper divisors (33494430).

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

21093090 is a wasteful number, since it uses less digits than its factorization.

21093090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 787.

The product of its (nonzero) digits is 486, while the sum is 24.

The square root of 21093090 is about 4592.7214154573. The cubic root of 21093090 is about 276.2994806367.

The spelling of 21093090 in words is "twenty-one million, ninety-three thousand, ninety".