21943786 has 4 divisors (see below), whose sum is σ = 32915682. Its totient is φ = 10971892.

The previous prime is 21943781. The next prime is 21943793. The reversal of 21943786 is 68734912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18757561 + 3186225 = 4331^2 + 1785^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21943781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5485945 + ... + 5485948.

Almost surely, 2^21943786 is an apocalyptic number.

21943786 is a deficient number, since it is larger than the sum of its proper divisors (10971896).

21943786 is a wasteful number, since it uses less digits than its factorization.

21943786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10971895.

The product of its digits is 72576, while the sum is 40.

The square root of 21943786 is about 4684.4194944518. The cubic root of 21943786 is about 279.9650721738.

The spelling of 21943786 in words is "twenty-one million, nine hundred forty-three thousand, seven hundred eighty-six".