21285234 has 32 divisors (see below), whose sum is σ = 47504640. Its totient is φ = 7064496.

The previous prime is 21285233. The next prime is 21285247. The reversal of 21285234 is 43258212.

It is a super-2 number, since 2×21285234² = 906122372869512, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21285198 and 21285207.

It is not an unprimeable number, because it can be changed into a prime (21285233) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 14247 + ... + 15669.

It is an arithmetic number, because the mean of its divisors is an integer number (1484520).

Almost surely, 2^21285234 is an apocalyptic number.

21285234 is an abundant number, since it is smaller than the sum of its proper divisors (26219406).

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

21285234 is a wasteful number, since it uses less digits than its factorization.

21285234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1711 (or 1705 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21285234 is about 4613.5923096867. The cubic root of 21285234 is about 277.1359140470.

The spelling of 21285234 in words is "twenty-one million, two hundred eighty-five thousand, two hundred thirty-four".