21090275 has 12 divisors (see below), whose sum is σ = 26263944. Its totient is φ = 16800000.

The previous prime is 21090271. The next prime is 21090299. The reversal of 21090275 is 57209012.

It is not a de Polignac number, because 21090275 - 2² = 21090271 is a prime.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21090271) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4595 + ... + 7955.

It is an arithmetic number, because the mean of its divisors is an integer number (2188662).

Almost surely, 2^21090275 is an apocalyptic number.

21090275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21090275 is a deficient number, since it is larger than the sum of its proper divisors (5173669).

21090275 is a wasteful number, since it uses less digits than its factorization.

21090275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3622 (or 3617 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21090275 is about 4592.4149420539. The cubic root of 21090275 is about 276.2871888128.

Adding to 21090275 its reverse (57209012), we get a palindrome (78299287).

The spelling of 21090275 in words is "twenty-one million, ninety thousand, two hundred seventy-five".