21185423 has 16 divisors (see below), whose sum is σ = 25072704. Its totient is φ = 17521920.

The previous prime is 21185419. The next prime is 21185441. The reversal of 21185423 is 32458112.

It is a cyclic number.

It is not a de Polignac number, because 21185423 - 2² = 21185419 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21185392 and 21185401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185413) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40403 + ... + 40923.

It is an arithmetic number, because the mean of its divisors is an integer number (1567044).

Almost surely, 2^21185423 is an apocalyptic number.

21185423 is a deficient number, since it is larger than the sum of its proper divisors (3887281).

21185423 is a wasteful number, since it uses less digits than its factorization.

21185423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722.

The product of its digits is 1920, while the sum is 26.

The square root of 21185423 is about 4602.7625400405. The cubic root of 21185423 is about 276.7020520538.

The spelling of 21185423 in words is "twenty-one million, one hundred eighty-five thousand, four hundred twenty-three".