21727855 has 4 divisors (see below), whose sum is σ = 26073432. Its totient is φ = 17382280.

The previous prime is 21727841. The next prime is 21727861. The reversal of 21727855 is 55872712.

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

It is not a de Polignac number, because 21727855 - 2¹⁵ = 21695087 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 3 ways as a sum of consecutive naturals, for example, 2172781 + ... + 2172790.

It is an arithmetic number, because the mean of its divisors is an integer number (6518358).

Almost surely, 2^21727855 is an apocalyptic number.

21727855 is a deficient number, since it is larger than the sum of its proper divisors (4345577).

21727855 is an equidigital number, since it uses as much as digits as its factorization.

21727855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4345576.

The product of its digits is 39200, while the sum is 37.

The square root of 21727855 is about 4661.3147287005. The cubic root of 21727855 is about 279.0437404390.

The spelling of 21727855 in words is "twenty-one million, seven hundred twenty-seven thousand, eight hundred fifty-five".