21131226 has 32 divisors (see below), whose sum is σ = 47387520. Its totient is φ = 6979392.

The previous prime is 21131191. The next prime is 21131251. The reversal of 21131226 is 62213112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21131199 and 21131208.

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, 4371 + ... + 7833.

It is an arithmetic number, because the mean of its divisors is an integer number (1480860).

Almost surely, 2^21131226 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21131226, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23693760).

21131226 is an abundant number, since it is smaller than the sum of its proper divisors (26256294).

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

21131226 is a wasteful number, since it uses less digits than its factorization.

21131226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3587 (or 3581 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 21131226 is about 4596.8713273269. The cubic root of 21131226 is about 276.4658955328.

Adding to 21131226 its reverse (62213112), we get a palindrome (83344338).

The spelling of 21131226 in words is "twenty-one million, one hundred thirty-one thousand, two hundred twenty-six".