21913989 has 8 divisors (see below), whose sum is σ = 29268480. Its totient is φ = 14584416.

The previous prime is 21913979. The next prime is 21914017. The reversal of 21913989 is 98931912.

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

It is not a de Polignac number, because 21913989 - 2⁷ = 21913861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21913989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21913979) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 4069 + ... + 7770.

It is an arithmetic number, because the mean of its divisors is an integer number (3658560).

Almost surely, 2^21913989 is an apocalyptic number.

It is an amenable number.

21913989 is a deficient number, since it is larger than the sum of its proper divisors (7354491).

21913989 is a wasteful number, since it uses less digits than its factorization.

21913989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12459.

The product of its digits is 34992, while the sum is 42.

The square root of 21913989 is about 4681.2379772876. The cubic root of 21913989 is about 279.8382952362.

The spelling of 21913989 in words is "twenty-one million, nine hundred thirteen thousand, nine hundred eighty-nine".