21879790 has 8 divisors (see below), whose sum is σ = 39383640. Its totient is φ = 8751912.

The previous prime is 21879743. The next prime is 21879817. The reversal of 21879790 is 9797812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093980 + ... + 1093999.

It is an arithmetic number, because the mean of its divisors is an integer number (4922955).

Almost surely, 2^21879790 is an apocalyptic number.

21879790 is a deficient number, since it is larger than the sum of its proper divisors (17503850).

21879790 is a wasteful number, since it uses less digits than its factorization.

21879790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2187986.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 21879790 is about 4677.5837779777. The cubic root of 21879790 is about 279.6926474402.

It can be divided in two parts, 218 and 79790, that added together give a palindrome (80008).

The spelling of 21879790 in words is "twenty-one million, eight hundred seventy-nine thousand, seven hundred ninety".