21091942 has 8 divisors (see below), whose sum is σ = 31701600. Its totient is φ = 10524744.

The previous prime is 21091937. The next prime is 21091949. The reversal of 21091942 is 24919012.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21091942.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21091949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9342 + ... + 11377.

It is an arithmetic number, because the mean of its divisors is an integer number (3962700).

Almost surely, 2^21091942 is an apocalyptic number.

21091942 is a deficient number, since it is larger than the sum of its proper divisors (10609658).

21091942 is a wasteful number, since it uses less digits than its factorization.

21091942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21230.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21091942 is about 4592.5964333915. The cubic root of 21091942 is about 276.2944679752.

The spelling of 21091942 in words is "twenty-one million, ninety-one thousand, nine hundred forty-two".