21921911 has 8 divisors (see below), whose sum is σ = 23950848. Its totient is φ = 19899000.

The previous prime is 21921901. The next prime is 21921917. The reversal of 21921911 is 11912912.

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

It is not a de Polignac number, because 21921911 - 2⁶ = 21921847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9896 + ... + 11906.

It is an arithmetic number, because the mean of its divisors is an integer number (2993856).

Almost surely, 2^21921911 is an apocalyptic number.

21921911 is a deficient number, since it is larger than the sum of its proper divisors (2028937).

21921911 is a wasteful number, since it uses less digits than its factorization.

21921911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3013.

The product of its digits is 324, while the sum is 26.

The square root of 21921911 is about 4682.0840445255. The cubic root of 21921911 is about 279.8720120839.

The spelling of 21921911 in words is "twenty-one million, nine hundred twenty-one thousand, nine hundred eleven".