21475786 has 4 divisors (see below), whose sum is σ = 32213682. Its totient is φ = 10737892.

The previous prime is 21475781. The next prime is 21475787. The reversal of 21475786 is 68757412.

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., 21335161 + 140625 = 4619^2 + 375^2 .

It is a super-2 number, since 2×21475786² = 922418768635592, which contains 22 as substring.

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 (21475781) by changing a digit.

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, 5368945 + ... + 5368948.

Almost surely, 2^21475786 is an apocalyptic number.

21475786 is a deficient number, since it is larger than the sum of its proper divisors (10737896).

21475786 is a wasteful number, since it uses less digits than its factorization.

21475786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10737895.

The product of its digits is 94080, while the sum is 40.

The square root of 21475786 is about 4634.1974493973. The cubic root of 21475786 is about 277.9604605361.

The spelling of 21475786 in words is "twenty-one million, four hundred seventy-five thousand, seven hundred eighty-six".