21250390 has 64 divisors (see below), whose sum is σ = 46531584. Its totient is φ = 6830208.

The previous prime is 21250351. The next prime is 21250393. The reversal of 21250390 is 9305212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21250393) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 107772 + ... + 107968.

It is an arithmetic number, because the mean of its divisors is an integer number (727056).

Almost surely, 2^21250390 is an apocalyptic number.

21250390 is an abundant number, since it is smaller than the sum of its proper divisors (25281194).

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

21250390 is a wasteful number, since it uses less digits than its factorization.

21250390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21250390 is about 4609.8145298916. The cubic root of 21250390 is about 276.9846073111.

The spelling of 21250390 in words is "twenty-one million, two hundred fifty thousand, three hundred ninety".