21519893 has 4 divisors (see below), whose sum is σ = 21728928. Its totient is φ = 21310860.

The previous prime is 21519877. The next prime is 21519907. The reversal of 21519893 is 39891512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21519893 - 2⁴ = 21519877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21519803) 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 3 ways as a sum of consecutive naturals, for example, 104363 + ... + 104568.

It is an arithmetic number, because the mean of its divisors is an integer number (5432232).

Almost surely, 2^21519893 is an apocalyptic number.

It is an amenable number.

21519893 is a deficient number, since it is larger than the sum of its proper divisors (209035).

21519893 is a wasteful number, since it uses less digits than its factorization.

21519893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209034.

The product of its digits is 19440, while the sum is 38.

The square root of 21519893 is about 4638.9538691390. The cubic root of 21519893 is about 278.1506222744.

The spelling of 21519893 in words is "twenty-one million, five hundred nineteen thousand, eight hundred ninety-three".