21521234 has 16 divisors (see below), whose sum is σ = 36960000. Its totient is φ = 9206784.

The previous prime is 21521183. The next prime is 21521249. The reversal of 21521234 is 43212512.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9767 + ... + 11765.

It is an arithmetic number, because the mean of its divisors is an integer number (2310000).

Almost surely, 2^21521234 is an apocalyptic number.

21521234 is a deficient number, since it is larger than the sum of its proper divisors (15438766).

21521234 is a wasteful number, since it uses less digits than its factorization.

21521234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2777.

The product of its digits is 480, while the sum is 20.

The square root of 21521234 is about 4639.0984037849. The cubic root of 21521234 is about 278.1563997541.

Adding to 21521234 its reverse (43212512), we get a palindrome (64733746).

The spelling of 21521234 in words is "twenty-one million, five hundred twenty-one thousand, two hundred thirty-four".