21293911 has 8 divisors (see below), whose sum is σ = 22767264. Its totient is φ = 19845120.

The previous prime is 21293903. The next prime is 21293939. The reversal of 21293911 is 11939212.

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

It is not a de Polignac number, because 21293911 - 2³ = 21293903 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21293911.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21293971) 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, 4330 + ... + 7831.

It is an arithmetic number, because the mean of its divisors is an integer number (2845908).

Almost surely, 2^21293911 is an apocalyptic number.

21293911 is a deficient number, since it is larger than the sum of its proper divisors (1473353).

21293911 is a wasteful number, since it uses less digits than its factorization.

21293911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12281.

The product of its digits is 972, while the sum is 28.

The square root of 21293911 is about 4614.5325873809. The cubic root of 21293911 is about 277.1735674055.

The spelling of 21293911 in words is "twenty-one million, two hundred ninety-three thousand, nine hundred eleven".