21736786 has 4 divisors (see below), whose sum is σ = 32605182. Its totient is φ = 10868392.

The previous prime is 21736769. The next prime is 21736823. The reversal of 21736786 is 68763712.

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., 13505625 + 8231161 = 3675^2 + 2869^2 .

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 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 as a sum of consecutive naturals, namely, 5434195 + ... + 5434198.

Almost surely, 2^21736786 is an apocalyptic number.

21736786 is a deficient number, since it is larger than the sum of its proper divisors (10868396).

21736786 is a wasteful number, since it uses less digits than its factorization.

21736786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10868395.

The product of its digits is 84672, while the sum is 40.

The square root of 21736786 is about 4662.2726218015. The cubic root of 21736786 is about 279.0819678399.

It can be divided in two parts, 21736 and 786, that added together give a palindrome (22522).

The spelling of 21736786 in words is "twenty-one million, seven hundred thirty-six thousand, seven hundred eighty-six".