21550871 has 12 divisors (see below), whose sum is σ = 22605744. Its totient is φ = 20532000.

The previous prime is 21550861. The next prime is 21550891. The reversal of 21550871 is 17805512.

It is a de Polignac number, because none of the positive numbers 2^k-21550871 is a prime.

It is a super-3 number, since 3×21550871³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 142646 + ... + 142796.

It is an arithmetic number, because the mean of its divisors is an integer number (1883812).

Almost surely, 2^21550871 is an apocalyptic number.

21550871 is a deficient number, since it is larger than the sum of its proper divisors (1054873).

21550871 is an equidigital number, since it uses as much as digits as its factorization.

21550871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 21550871 is about 4642.2915677497. The cubic root of 21550871 is about 278.2840247152.

The spelling of 21550871 in words is "twenty-one million, five hundred fifty thousand, eight hundred seventy-one".