21550417 has 16 divisors (see below), whose sum is σ = 25242624. Its totient is φ = 18018000.

The previous prime is 21550409. The next prime is 21550447. The reversal of 21550417 is 71405512.

It is not a de Polignac number, because 21550417 - 2³ = 21550409 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21550391 and 21550400.

It is not an unprimeable number, because it can be changed into a prime (21550447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 64942 + ... + 65272.

It is an arithmetic number, because the mean of its divisors is an integer number (1577664).

Almost surely, 2^21550417 is an apocalyptic number.

It is an amenable number.

21550417 is a deficient number, since it is larger than the sum of its proper divisors (3692207).

21550417 is a wasteful number, since it uses less digits than its factorization.

21550417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540.

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 21550417 is about 4642.2426692279. The cubic root of 21550417 is about 278.2820705508.

Adding to 21550417 its reverse (71405512), we get a palindrome (92955929).

The spelling of 21550417 in words is "twenty-one million, five hundred fifty thousand, four hundred seventeen".