21871205 has 8 divisors (see below), whose sum is σ = 26371104. Its totient is φ = 17413200.

The previous prime is 21871169. The next prime is 21871207. The reversal of 21871205 is 50217812.

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

It is not a de Polignac number, because 21871205 - 2⁶ = 21871141 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 (21871207) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9311 + ... + 11420.

It is an arithmetic number, because the mean of its divisors is an integer number (3296388).

Almost surely, 2^21871205 is an apocalyptic number.

It is an amenable number.

21871205 is a deficient number, since it is larger than the sum of its proper divisors (4499899).

21871205 is a wasteful number, since it uses less digits than its factorization.

21871205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20947.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21871205 is about 4676.6660133048. Note that the first 3 decimals coincide. The cubic root of 21871205 is about 279.6560615391.

The spelling of 21871205 in words is "twenty-one million, eight hundred seventy-one thousand, two hundred five".