21499173 has 6 divisors (see below), whose sum is σ = 31054374. Its totient is φ = 14332776.

The previous prime is 21499171. The next prime is 21499199. The reversal of 21499173 is 37199412.

It can be written as a sum of positive squares in only one way, i.e., 17164449 + 4334724 = 4143^2 + 2082^2 .

It is not a de Polignac number, because 21499173 - 2¹ = 21499171 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21499171) 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, 1194390 + ... + 1194407.

It is an arithmetic number, because the mean of its divisors is an integer number (5175729).

Almost surely, 2^21499173 is an apocalyptic number.

It is an amenable number.

21499173 is a deficient number, since it is larger than the sum of its proper divisors (9555201).

21499173 is a wasteful number, since it uses less digits than its factorization.

21499173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2388803 (or 2388800 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 21499173 is about 4636.7200691868. The cubic root of 21499173 is about 278.0613230143.

The spelling of 21499173 in words is "twenty-one million, four hundred ninety-nine thousand, one hundred seventy-three".