21082087 has 4 divisors (see below), whose sum is σ = 22703800. Its totient is φ = 19460376.

The previous prime is 21082063. The next prime is 21082093. The reversal of 21082087 is 78028012.

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

It is not a de Polignac number, because 21082087 - 2¹⁵ = 21049319 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 (21082687) 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, 810837 + ... + 810862.

It is an arithmetic number, because the mean of its divisors is an integer number (5675950).

Almost surely, 2^21082087 is an apocalyptic number.

21082087 is a deficient number, since it is larger than the sum of its proper divisors (1621713).

21082087 is a wasteful number, since it uses less digits than its factorization.

21082087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1621712.

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 21082087 is about 4591.5233855443. The cubic root of 21082087 is about 276.2514293245.

The spelling of 21082087 in words is "twenty-one million, eighty-two thousand, eighty-seven".