21377855 has 4 divisors (see below), whose sum is σ = 25653432. Its totient is φ = 17102280.

The previous prime is 21377827. The next prime is 21377861. The reversal of 21377855 is 55877312.

It is a happy number.

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

It is not a de Polignac number, because 21377855 - 2⁸ = 21377599 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, 2137781 + ... + 2137790.

It is an arithmetic number, because the mean of its divisors is an integer number (6413358).

Almost surely, 2^21377855 is an apocalyptic number.

21377855 is a deficient number, since it is larger than the sum of its proper divisors (4275577).

21377855 is an equidigital number, since it uses as much as digits as its factorization.

21377855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4275576.

The product of its digits is 58800, while the sum is 38.

The square root of 21377855 is about 4623.6192533555. The cubic root of 21377855 is about 277.5373106773.

The spelling of 21377855 in words is "twenty-one million, three hundred seventy-seven thousand, eight hundred fifty-five".