21475618 has 4 divisors (see below), whose sum is σ = 32213430. Its totient is φ = 10737808.

The previous prime is 21475613. The next prime is 21475621. The reversal of 21475618 is 81657412.

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., 19562929 + 1912689 = 4423^2 + 1383^2 .

It is a super-2 number, since 2×21475618² = 922404336963848, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21475613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5368903 + ... + 5368906.

Almost surely, 2^21475618 is an apocalyptic number.

21475618 is a deficient number, since it is larger than the sum of its proper divisors (10737812).

21475618 is a wasteful number, since it uses less digits than its factorization.

21475618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10737811.

The product of its digits is 13440, while the sum is 34.

The square root of 21475618 is about 4634.1793232459. The cubic root of 21475618 is about 277.9597357279.

The spelling of 21475618 in words is "twenty-one million, four hundred seventy-five thousand, six hundred eighteen".