21290919 has 24 divisors (see below), whose sum is σ = 32492880. Its totient is φ = 12324864.

The previous prime is 21290903. The next prime is 21290921. The reversal of 21290919 is 91909212.

It is not a de Polignac number, because 21290919 - 2⁴ = 21290903 is a prime.

It is a super-2 number, since 2×21290919² = 906606463729122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21290919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21290999) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10327 + ... + 12215.

It is an arithmetic number, because the mean of its divisors is an integer number (1353870).

Almost surely, 2^21290919 is an apocalyptic number.

21290919 is a deficient number, since it is larger than the sum of its proper divisors (11201961).

21290919 is a wasteful number, since it uses less digits than its factorization.

21290919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1939 (or 1922 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 21290919 is about 4614.2083828106. The cubic root of 21290919 is about 277.1605849437.

It can be divided in two parts, 2 and 1290919, that added together give a palindrome (1290921).

The spelling of 21290919 in words is "twenty-one million, two hundred ninety thousand, nine hundred nineteen".