21519091 has 16 divisors (see below), whose sum is σ = 24261120. Its totient is φ = 18918880.

The previous prime is 21519083. The next prime is 21519101. The reversal of 21519091 is 19091512.

It is a cyclic number.

It is not a de Polignac number, because 21519091 - 2³ = 21519083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21519061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55125 + ... + 55513.

It is an arithmetic number, because the mean of its divisors is an integer number (1516320).

Almost surely, 2^21519091 is an apocalyptic number.

21519091 is a deficient number, since it is larger than the sum of its proper divisors (2742029).

21519091 is a wasteful number, since it uses less digits than its factorization.

21519091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 21519091 is about 4638.8674264307. The cubic root of 21519091 is about 278.1471668736.

It can be divided in two parts, 215 and 19091, that added together give a triangular number (19306 = T₁₉₆).

The spelling of 21519091 in words is "twenty-one million, five hundred nineteen thousand, ninety-one".