21537234 has 12 divisors (see below), whose sum is σ = 46664046. Its totient is φ = 7179072.

The previous prime is 21537179. The next prime is 21537251. The reversal of 21537234 is 43273512.

It can be written as a sum of positive squares in only one way, i.e., 12981609 + 8555625 = 3603^2 + 2925^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21537198 and 21537207.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 598239 + ... + 598274.

Almost surely, 2^21537234 is an apocalyptic number.

21537234 is an abundant number, since it is smaller than the sum of its proper divisors (25126812).

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

21537234 is a wasteful number, since it uses less digits than its factorization.

21537234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1196521 (or 1196518 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21537234 is about 4640.8225564010. The cubic root of 21537234 is about 278.2253146367.

The spelling of 21537234 in words is "twenty-one million, five hundred thirty-seven thousand, two hundred thirty-four".