21617811 has 12 divisors (see below), whose sum is σ = 31347888. Its totient is φ = 14355504.

The previous prime is 21617809. The next prime is 21617821. The reversal of 21617811 is 11871612.

It is not a de Polignac number, because 21617811 - 2¹ = 21617809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21617821) 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, 2200 + ... + 6933.

It is an arithmetic number, because the mean of its divisors is an integer number (2612324).

Almost surely, 2^21617811 is an apocalyptic number.

21617811 is a deficient number, since it is larger than the sum of its proper divisors (9730077).

21617811 is a wasteful number, since it uses less digits than its factorization.

21617811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9402 (or 9399 counting only the distinct ones).

The product of its digits is 672, while the sum is 27.

The square root of 21617811 is about 4649.4957791141. The cubic root of 21617811 is about 278.5718565223.

The spelling of 21617811 in words is "twenty-one million, six hundred seventeen thousand, eight hundred eleven".