21731226 has 32 divisors (see below), whose sum is σ = 47996928. Its totient is φ = 6504240.

The previous prime is 21731191. The next prime is 21731239. The reversal of 21731226 is 62213712.

It is a junction number, because it is equal to n+sod(n) for n = 21731196 and 21731205.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3495 + ... + 7461.

It is an arithmetic number, because the mean of its divisors is an integer number (1499904).

Almost surely, 2^21731226 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21731226, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23998464).

21731226 is an abundant number, since it is smaller than the sum of its proper divisors (26265702).

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

21731226 is a wasteful number, since it uses less digits than its factorization.

21731226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4066.

The product of its digits is 1008, while the sum is 24.

The square root of 21731226 is about 4661.6763079390. The cubic root of 21731226 is about 279.0581705766.

Adding to 21731226 its reverse (62213712), we get a palindrome (83944938).

The spelling of 21731226 in words is "twenty-one million, seven hundred thirty-one thousand, two hundred twenty-six".