21086553 has 4 divisors (see below), whose sum is σ = 28115408. Its totient is φ = 14057700.

The previous prime is 21086543. The next prime is 21086563. The reversal of 21086553 is 35568012.

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 an interprime number because it is at equal distance from previous prime (21086543) and next prime (21086563).

It is not a de Polignac number, because 21086553 - 2¹⁰ = 21085529 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21086553.

It is not an unprimeable number, because it can be changed into a prime (21086543) 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, 3514423 + ... + 3514428.

It is an arithmetic number, because the mean of its divisors is an integer number (7028852).

Almost surely, 2^21086553 is an apocalyptic number.

It is an amenable number.

21086553 is a deficient number, since it is larger than the sum of its proper divisors (7028855).

21086553 is an equidigital number, since it uses as much as digits as its factorization.

21086553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7028854.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21086553 is about 4592.0096907563. The cubic root of 21086553 is about 276.2709348535.

The spelling of 21086553 in words is "twenty-one million, eighty-six thousand, five hundred fifty-three".