21152255 has 4 divisors (see below), whose sum is σ = 25382712. Its totient is φ = 16921800.

The previous prime is 21152239. The next prime is 21152291. The reversal of 21152255 is 55225112.

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

It is not a de Polignac number, because 21152255 - 2⁴ = 21152239 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 21152255.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115221 + ... + 2115230.

It is an arithmetic number, because the mean of its divisors is an integer number (6345678).

Almost surely, 2^21152255 is an apocalyptic number.

21152255 is a deficient number, since it is larger than the sum of its proper divisors (4230457).

21152255 is an equidigital number, since it uses as much as digits as its factorization.

21152255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230456.

The product of its digits is 1000, while the sum is 23.

The square root of 21152255 is about 4599.1580751264. The cubic root of 21152255 is about 276.5575746088.

Adding to 21152255 its reverse (55225112), we get a palindrome (76377367).

The spelling of 21152255 in words is "twenty-one million, one hundred fifty-two thousand, two hundred fifty-five".