21939091 has 8 divisors (see below), whose sum is σ = 23486400. Its totient is φ = 20431080.

The previous prime is 21939067. The next prime is 21939097. The reversal of 21939091 is 19093912.

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

It is not a de Polignac number, because 21939091 - 2¹⁵ = 21906323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21939097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8665 + ... + 10906.

It is an arithmetic number, because the mean of its divisors is an integer number (2935800).

Almost surely, 2^21939091 is an apocalyptic number.

21939091 is a deficient number, since it is larger than the sum of its proper divisors (1547309).

21939091 is a wasteful number, since it uses less digits than its factorization.

21939091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19649.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 21939091 is about 4683.9183383146. The cubic root of 21939091 is about 279.9451040339.

The spelling of 21939091 in words is "twenty-one million, nine hundred thirty-nine thousand, ninety-one".