21031396 has 9 divisors (see below), whose sum is σ = 36821001. Its totient is φ = 10511112.

The previous prime is 21031393. The next prime is 21031421. The reversal of 21031396 is 69313012.

The square root of 21031396 is 4586.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 6100900 + 14930496 = 2470^2 + 3864^2 .

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21031396.

It is not an unprimeable number, because it can be changed into a prime (21031391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 8026 + ... + 10318.

Almost surely, 2^21031396 is an apocalyptic number.

21031396 is the 4586-th square number.

It is an amenable number.

21031396 is a deficient number, since it is larger than the sum of its proper divisors (15789605).

21031396 is an frugal number, since it uses more digits than its factorization.

21031396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4590 (or 2295 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 25.

The cubic root of 21031396 is about 276.0298399439.

Multiplying 21031396 by its sum of digits (25), we get a square (525784900 = 22930²).

The spelling of 21031396 in words is "twenty-one million, thirty-one thousand, three hundred ninety-six".