21263855 has 16 divisors (see below), whose sum is σ = 27306720. Its totient is φ = 15839232.

The previous prime is 21263819. The next prime is 21263867. The reversal of 21263855 is 55836212.

It is a cyclic number.

It is not a de Polignac number, because 21263855 - 2¹⁸ = 21001711 is a prime.

It is a super-2 number, since 2×21263855² = 904303058922050, which contains 22 as substring.

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, 6956 + ... + 9534.

It is an arithmetic number, because the mean of its divisors is an integer number (1706670).

Almost surely, 2^21263855 is an apocalyptic number.

21263855 is a deficient number, since it is larger than the sum of its proper divisors (6042865).

21263855 is a wasteful number, since it uses less digits than its factorization.

21263855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2698.

The product of its digits is 14400, while the sum is 32.

The square root of 21263855 is about 4611.2747695187. The cubic root of 21263855 is about 277.0430973792.

The spelling of 21263855 in words is "twenty-one million, two hundred sixty-three thousand, eight hundred fifty-five".