21241990 has 64 divisors (see below), whose sum is σ = 48729600. Its totient is φ = 6609120.

The previous prime is 21241973. The next prime is 21241991. The reversal of 21241990 is 9914212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21241991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37449 + ... + 38011.

It is an arithmetic number, because the mean of its divisors is an integer number (761400).

Almost surely, 2^21241990 is an apocalyptic number.

21241990 is an abundant number, since it is smaller than the sum of its proper divisors (27487610).

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

21241990 is a wasteful number, since it uses less digits than its factorization.

21241990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 602 (or 588 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21241990 is about 4608.9033402752. The cubic root of 21241990 is about 276.9481063757.

It can be divided in two parts, 2124 and 1990, that added together give a palindrome (4114).

The spelling of 21241990 in words is "twenty-one million, two hundred forty-one thousand, nine hundred ninety".