21311276 has 36 divisors (see below), whose sum is σ = 43647408. Its totient is φ = 9104592.

The previous prime is 21311261. The next prime is 21311347. The reversal of 21311276 is 67211312.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67070 + ... + 67386.

It is an arithmetic number, because the mean of its divisors is an integer number (1212428).

Almost surely, 2^21311276 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21311276, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21823704).

21311276 is an abundant number, since it is smaller than the sum of its proper divisors (22336132).

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

21311276 is an frugal number, since it uses more digits than its factorization.

21311276 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356 (or 326 counting only the distinct ones).

The product of its digits is 504, while the sum is 23.

The square root of 21311276 is about 4616.4137596190. The cubic root of 21311276 is about 277.2488911484.

Adding to 21311276 its reverse (67211312), we get a palindrome (88522588).

The spelling of 21311276 in words is "twenty-one million, three hundred eleven thousand, two hundred seventy-six".