21500871 has 8 divisors (see below), whose sum is σ = 32763264. Its totient is φ = 12286200.

The previous prime is 21500833. The next prime is 21500893. The reversal of 21500871 is 17800512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21500871 - 2¹⁴ = 21484487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21500821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 511905 + ... + 511946.

It is an arithmetic number, because the mean of its divisors is an integer number (4095408).

Almost surely, 2^21500871 is an apocalyptic number.

21500871 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21500871 is a deficient number, since it is larger than the sum of its proper divisors (11262393).

21500871 is a wasteful number, since it uses less digits than its factorization.

21500871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023861.

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 21500871 is about 4636.9031691421. The cubic root of 21500871 is about 278.0686432291.

The spelling of 21500871 in words is "twenty-one million, five hundred thousand, eight hundred seventy-one".