21188290 has 32 divisors (see below), whose sum is σ = 42145920. Its totient is φ = 7628544.

The previous prime is 21188261. The next prime is 21188329. The reversal of 21188290 is 9288112.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1201 + ... + 6619.

It is an arithmetic number, because the mean of its divisors is an integer number (1317060).

Almost surely, 2^21188290 is an apocalyptic number.

21188290 is a deficient number, since it is larger than the sum of its proper divisors (20957630).

21188290 is a wasteful number, since it uses less digits than its factorization.

21188290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5466.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21188290 is about 4603.0739729012. The cubic root of 21188290 is about 276.7145334189.

The spelling of 21188290 in words is "twenty-one million, one hundred eighty-eight thousand, two hundred ninety".