21271855 has 16 divisors (see below), whose sum is σ = 28602144. Its totient is φ = 15050880.

The previous prime is 21271843. The next prime is 21271883. The reversal of 21271855 is 55817212.

It is not a de Polignac number, because 21271855 - 2⁷ = 21271727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3192 + ... + 7261.

It is an arithmetic number, because the mean of its divisors is an integer number (1787634).

Almost surely, 2^21271855 is an apocalyptic number.

21271855 is a deficient number, since it is larger than the sum of its proper divisors (7330289).

21271855 is a wasteful number, since it uses less digits than its factorization.

21271855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10506.

The product of its digits is 5600, while the sum is 31.

The square root of 21271855 is about 4612.1421270382. The cubic root of 21271855 is about 277.0778365628.

The spelling of 21271855 in words is "twenty-one million, two hundred seventy-one thousand, eight hundred fifty-five".