21117291 has 8 divisors (see below), whose sum is σ = 30322320. Its totient is φ = 12995232.

The previous prime is 21117277. The next prime is 21117311. The reversal of 21117291 is 19271112.

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

It is not a de Polignac number, because 21117291 - 2⁵ = 21117259 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21117251) 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, 270696 + ... + 270773.

It is an arithmetic number, because the mean of its divisors is an integer number (3790290).

Almost surely, 2^21117291 is an apocalyptic number.

21117291 is a deficient number, since it is larger than the sum of its proper divisors (9205029).

21117291 is a wasteful number, since it uses less digits than its factorization.

21117291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541485.

The product of its digits is 252, while the sum is 24.

The square root of 21117291 is about 4595.3553725474. The cubic root of 21117291 is about 276.4051103008.

The spelling of 21117291 in words is "twenty-one million, one hundred seventeen thousand, two hundred ninety-one".