21871355 has 12 divisors (see below), whose sum is σ = 28849296. Its totient is φ = 15906000.

The previous prime is 21871331. The next prime is 21871379. The reversal of 21871355 is 55317812.

It is an interprime number because it is at equal distance from previous prime (21871331) and next prime (21871379).

It is not a de Polignac number, because 21871355 - 2⁸ = 21871099 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17471 + ... + 18680.

It is an arithmetic number, because the mean of its divisors is an integer number (2404108).

Almost surely, 2^21871355 is an apocalyptic number.

21871355 is a deficient number, since it is larger than the sum of its proper divisors (6977941).

21871355 is a wasteful number, since it uses less digits than its factorization.

21871355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36178 (or 36167 counting only the distinct ones).

The product of its digits is 8400, while the sum is 32.

The square root of 21871355 is about 4676.6820503430. The cubic root of 21871355 is about 279.6567008625.

The spelling of 21871355 in words is "twenty-one million, eight hundred seventy-one thousand, three hundred fifty-five".