21550775 has 6 divisors (see below), whose sum is σ = 26722992. Its totient is φ = 17240600.

The previous prime is 21550691. The next prime is 21550777. The reversal of 21550775 is 57705512.

It is not a de Polignac number, because 21550775 - 2⁸ = 21550519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550777) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 430991 + ... + 431040.

It is an arithmetic number, because the mean of its divisors is an integer number (4453832).

Almost surely, 2^21550775 is an apocalyptic number.

21550775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21550775 is a deficient number, since it is larger than the sum of its proper divisors (5172217).

21550775 is an equidigital number, since it uses as much as digits as its factorization.

21550775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862041 (or 862036 counting only the distinct ones).

The product of its (nonzero) digits is 12250, while the sum is 32.

The square root of 21550775 is about 4642.2812280171. The cubic root of 21550775 is about 278.2836115021.

The spelling of 21550775 in words is "twenty-one million, five hundred fifty thousand, seven hundred seventy-five".