21786396 has 12 divisors (see below), whose sum is σ = 50834952. Its totient is φ = 7262128.

The previous prime is 21786389. The next prime is 21786403. The reversal of 21786396 is 69368712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21786389) and next prime (21786403).

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 907755 + ... + 907778.

It is an arithmetic number, because the mean of its divisors is an integer number (4236246).

Almost surely, 2^21786396 is an apocalyptic number.

It is an amenable number.

21786396 is an abundant number, since it is smaller than the sum of its proper divisors (29048556).

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

21786396 is a wasteful number, since it uses less digits than its factorization.

21786396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1815540 (or 1815538 counting only the distinct ones).

The product of its digits is 108864, while the sum is 42.

The square root of 21786396 is about 4667.5899562836. The cubic root of 21786396 is about 279.2941233493.

The spelling of 21786396 in words is "twenty-one million, seven hundred eighty-six thousand, three hundred ninety-six".