21519853 has 4 divisors (see below), whose sum is σ = 21597820. Its totient is φ = 21441888.

The previous prime is 21519851. The next prime is 21519857. The reversal of 21519853 is 35891512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9108324 + 12411529 = 3018^2 + 3523^2 .

It is a cyclic number.

It is not a de Polignac number, because 21519853 - 2¹ = 21519851 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 (21519851) 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, 38568 + ... + 39121.

It is an arithmetic number, because the mean of its divisors is an integer number (5399455).

Almost surely, 2^21519853 is an apocalyptic number.

It is an amenable number.

21519853 is a deficient number, since it is larger than the sum of its proper divisors (77967).

21519853 is an equidigital number, since it uses as much as digits as its factorization.

21519853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77966.

The product of its digits is 10800, while the sum is 34.

The square root of 21519853 is about 4638.9495578202. The cubic root of 21519853 is about 278.1504499373.

The spelling of 21519853 in words is "twenty-one million, five hundred nineteen thousand, eight hundred fifty-three".