21476387 has 4 divisors (see below), whose sum is σ = 21748320. Its totient is φ = 21204456.

The previous prime is 21476383. The next prime is 21476401. The reversal of 21476387 is 78367412.

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 21476387 - 2² = 21476383 is a prime.

It is a super-3 number, since 3×21476387³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21476387.

It is not an unprimeable number, because it can be changed into a prime (21476383) 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, 135848 + ... + 136005.

It is an arithmetic number, because the mean of its divisors is an integer number (5437080).

Almost surely, 2^21476387 is an apocalyptic number.

21476387 is a deficient number, since it is larger than the sum of its proper divisors (271933).

21476387 is an equidigital number, since it uses as much as digits as its factorization.

21476387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271932.

The product of its digits is 56448, while the sum is 38.

The square root of 21476387 is about 4634.2622929653. The cubic root of 21476387 is about 277.9630534203.

The spelling of 21476387 in words is "twenty-one million, four hundred seventy-six thousand, three hundred eighty-seven".