21475887 has 4 divisors (see below), whose sum is σ = 28634520. Its totient is φ = 14317256.

The previous prime is 21475837. The next prime is 21475889. The reversal of 21475887 is 78857412.

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

It is a cyclic number.

It is not a de Polignac number, because 21475887 - 2¹⁵ = 21443119 is a prime.

It is a super-2 number, since 2×21475887² = 922427444873538, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21475889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3579312 + ... + 3579317.

It is an arithmetic number, because the mean of its divisors is an integer number (7158630).

Almost surely, 2^21475887 is an apocalyptic number.

21475887 is a deficient number, since it is larger than the sum of its proper divisors (7158633).

21475887 is an equidigital number, since it uses as much as digits as its factorization.

21475887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7158632.

The product of its digits is 125440, while the sum is 42.

The square root of 21475887 is about 4634.2083466327. The cubic root of 21475887 is about 277.9608962821.

The spelling of 21475887 in words is "twenty-one million, four hundred seventy-five thousand, eight hundred eighty-seven".