21921263 has 8 divisors (see below), whose sum is σ = 26980128. Its totient is φ = 17344224.

The previous prime is 21921259. The next prime is 21921281. The reversal of 21921263 is 36212912.

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

It is a cyclic number.

It is not a de Polignac number, because 21921263 - 2² = 21921259 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921253) 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, 120356 + ... + 120537.

It is an arithmetic number, because the mean of its divisors is an integer number (3372516).

Almost surely, 2^21921263 is an apocalyptic number.

21921263 is a deficient number, since it is larger than the sum of its proper divisors (5058865).

21921263 is a wasteful number, since it uses less digits than its factorization.

21921263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240913.

The product of its digits is 1296, while the sum is 26.

The square root of 21921263 is about 4682.0148440602. The cubic root of 21921263 is about 279.8692544343.

The spelling of 21921263 in words is "twenty-one million, nine hundred twenty-one thousand, two hundred sixty-three".