21275986 has 4 divisors (see below), whose sum is σ = 31913982. Its totient is φ = 10637992.

The previous prime is 21275983. The next prime is 21276023. The reversal of 21275986 is 68957212.

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., 19228225 + 2047761 = 4385^2 + 1431^2 .

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 (21275981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5318995 + ... + 5318998.

Almost surely, 2^21275986 is an apocalyptic number.

21275986 is a deficient number, since it is larger than the sum of its proper divisors (10637996).

21275986 is a wasteful number, since it uses less digits than its factorization.

21275986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10637995.

The product of its digits is 60480, while the sum is 40.

The square root of 21275986 is about 4612.5899449225. The cubic root of 21275986 is about 277.0957715988.

The spelling of 21275986 in words is "twenty-one million, two hundred seventy-five thousand, nine hundred eighty-six".