21909151 has 8 divisors (see below), whose sum is σ = 24090624. Its totient is φ = 19759320.

The previous prime is 21909131. The next prime is 21909161. The reversal of 21909151 is 15190912.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21909151 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 (21909101) 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, 6445 + ... + 9238.

It is an arithmetic number, because the mean of its divisors is an integer number (3011328).

Almost surely, 2^21909151 is an apocalyptic number.

21909151 is a deficient number, since it is larger than the sum of its proper divisors (2181473).

21909151 is a wasteful number, since it uses less digits than its factorization.

21909151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15821.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 21909151 is about 4680.7212051136. The cubic root of 21909151 is about 279.8177002133.

The spelling of 21909151 in words is "twenty-one million, nine hundred nine thousand, one hundred fifty-one".