21478887 has 12 divisors (see below), whose sum is σ = 31747144. Its totient is φ = 13986000.

The previous prime is 21478883. The next prime is 21478901. The reversal of 21478887 is 78887412.

It is not a de Polignac number, because 21478887 - 2² = 21478883 is a prime.

It is a super-2 number, since 2×21478887² = 922685173517538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27364 + ... + 28137.

Almost surely, 2^21478887 is an apocalyptic number.

21478887 is a deficient number, since it is larger than the sum of its proper divisors (10268257).

21478887 is a wasteful number, since it uses less digits than its factorization.

21478887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55550 (or 55547 counting only the distinct ones).

The product of its digits is 200704, while the sum is 45.

The square root of 21478887 is about 4634.5320152093. The cubic root of 21478887 is about 277.9738386092.

The spelling of 21478887 in words is "twenty-one million, four hundred seventy-eight thousand, eight hundred eighty-seven".