21225990 has 32 divisors (see below), whose sum is σ = 51114240. Its totient is φ = 5641184.

The previous prime is 21225989. The next prime is 21226001. The reversal of 21225990 is 9952212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9391 + ... + 11429.

It is an arithmetic number, because the mean of its divisors is an integer number (1597320).

Almost surely, 2^21225990 is an apocalyptic number.

21225990 is an abundant number, since it is smaller than the sum of its proper divisors (29888250).

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

21225990 is a wasteful number, since it uses less digits than its factorization.

21225990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2396.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 21225990 is about 4607.1672424604. The cubic root of 21225990 is about 276.8785541551.

The spelling of 21225990 in words is "twenty-one million, two hundred twenty-five thousand, nine hundred ninety".