21191427 has 12 divisors (see below), whose sum is σ = 30657744. Its totient is φ = 14105520.

The previous prime is 21191393. The next prime is 21191447. The reversal of 21191427 is 72419112.

It is not a de Polignac number, because 21191427 - 2⁸ = 21191171 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21191427.

It is not an unprimeable number, because it can be changed into a prime (21191447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5977 + ... + 8837.

It is an arithmetic number, because the mean of its divisors is an integer number (2554812).

Almost surely, 2^21191427 is an apocalyptic number.

21191427 is a deficient number, since it is larger than the sum of its proper divisors (9466317).

21191427 is a wasteful number, since it uses less digits than its factorization.

21191427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3690 (or 3687 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 21191427 is about 4603.4147108424. The cubic root of 21191427 is about 276.7281889279.

The spelling of 21191427 in words is "twenty-one million, one hundred ninety-one thousand, four hundred twenty-seven".