21842387 has 12 divisors (see below), whose sum is σ = 26514576. Its totient is φ = 17907120.

The previous prime is 21842377. The next prime is 21842393. The reversal of 21842387 is 78324812.

It is not a de Polignac number, because 21842387 - 2⁸ = 21842131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21842347) 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 in 11 ways as a sum of consecutive naturals, for example, 8564 + ... + 10817.

It is an arithmetic number, because the mean of its divisors is an integer number (2209548).

Almost surely, 2^21842387 is an apocalyptic number.

21842387 is a deficient number, since it is larger than the sum of its proper divisors (4672189).

21842387 is a wasteful number, since it uses less digits than its factorization.

21842387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19418 (or 19411 counting only the distinct ones).

The product of its digits is 21504, while the sum is 35.

The square root of 21842387 is about 4673.5839566654. The cubic root of 21842387 is about 279.5331804785.

The spelling of 21842387 in words is "twenty-one million, eight hundred forty-two thousand, three hundred eighty-seven".