21267655 has 4 divisors (see below), whose sum is σ = 25521192. Its totient is φ = 17014120.

The previous prime is 21267619. The next prime is 21267679. The reversal of 21267655 is 55676212.

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

It is not a de Polignac number, because 21267655 - 2¹⁹ = 20743367 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 21267655.

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, 2126761 + ... + 2126770.

It is an arithmetic number, because the mean of its divisors is an integer number (6380298).

Almost surely, 2^21267655 is an apocalyptic number.

21267655 is a deficient number, since it is larger than the sum of its proper divisors (4253537).

21267655 is an equidigital number, since it uses as much as digits as its factorization.

21267655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4253536.

The product of its digits is 25200, while the sum is 34.

The square root of 21267655 is about 4611.6867846809. The cubic root of 21267655 is about 277.0595995777.

The spelling of 21267655 in words is "twenty-one million, two hundred sixty-seven thousand, six hundred fifty-five".