21170817 has 12 divisors (see below), whose sum is σ = 30672720. Its totient is φ = 14071128.

The previous prime is 21170789. The next prime is 21170857. The reversal of 21170817 is 71807112.

It is not a de Polignac number, because 21170817 - 2⁶ = 21170753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21170857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 267 + ... + 6512.

It is an arithmetic number, because the mean of its divisors is an integer number (2556060).

Almost surely, 2^21170817 is an apocalyptic number.

It is an amenable number.

21170817 is a deficient number, since it is larger than the sum of its proper divisors (9501903).

21170817 is a wasteful number, since it uses less digits than its factorization.

21170817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7132 (or 7129 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 21170817 is about 4601.1756106456. The cubic root of 21170817 is about 276.6384479534.

Adding to 21170817 its reverse (71807112), we get a palindrome (92977929).

The spelling of 21170817 in words is "twenty-one million, one hundred seventy thousand, eight hundred seventeen".