21973236 has 12 divisors (see below), whose sum is σ = 51270912. Its totient is φ = 7324408.

The previous prime is 21973229. The next prime is 21973247. The reversal of 21973236 is 63237912.

It is a happy number.

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

It is a plaindrome in base 11.

It is a zygodrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21973197 and 21973206.

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, 915540 + ... + 915563.

It is an arithmetic number, because the mean of its divisors is an integer number (4272576).

Almost surely, 2^21973236 is an apocalyptic number.

It is an amenable number.

21973236 is an abundant number, since it is smaller than the sum of its proper divisors (29297676).

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

21973236 is a wasteful number, since it uses less digits than its factorization.

21973236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1831110 (or 1831108 counting only the distinct ones).

The product of its digits is 13608, while the sum is 33.

The square root of 21973236 is about 4687.5618395921. The cubic root of 21973236 is about 280.0902600166.

The spelling of 21973236 in words is "twenty-one million, nine hundred seventy-three thousand, two hundred thirty-six".