21140087 has 4 divisors (see below), whose sum is σ = 21178200. Its totient is φ = 21101976.

The previous prime is 21140069. The next prime is 21140089. The reversal of 21140087 is 78004112.

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 21140087 - 2⁸ = 21139831 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140089) 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, 18212 + ... + 19337.

It is an arithmetic number, because the mean of its divisors is an integer number (5294550).

Almost surely, 2^21140087 is an apocalyptic number.

21140087 is a deficient number, since it is larger than the sum of its proper divisors (38113).

21140087 is an equidigital number, since it uses as much as digits as its factorization.

21140087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38112.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21140087 is about 4597.8350340133. The cubic root of 21140087 is about 276.5045338014.

Adding to 21140087 its reverse (78004112), we get a palindrome (99144199).

The spelling of 21140087 in words is "twenty-one million, one hundred forty thousand, eighty-seven".