21173850 has 72 divisors (see below), whose sum is σ = 57412992. Its totient is φ = 5594400.

The previous prime is 21173849. The next prime is 21173903. The reversal of 21173850 is 5837112.

It is a congruent number.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 94839 + ... + 95061.

Almost surely, 2^21173850 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21173850, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28706496).

21173850 is an abundant number, since it is smaller than the sum of its proper divisors (36239142).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21173850 is a wasteful number, since it uses less digits than its factorization.

21173850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452 (or 444 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21173850 is about 4601.5051885226. The cubic root of 21173850 is about 276.6516580300.

The spelling of 21173850 in words is "twenty-one million, one hundred seventy-three thousand, eight hundred fifty".