21871361 has 4 divisors (see below), whose sum is σ = 21888000. Its totient is φ = 21854724.

The previous prime is 21871331. The next prime is 21871379. The reversal of 21871361 is 16317812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21871361 - 2¹⁰ = 21870337 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21871331) 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, 6161 + ... + 9038.

It is an arithmetic number, because the mean of its divisors is an integer number (5472000).

Almost surely, 2^21871361 is an apocalyptic number.

It is an amenable number.

21871361 is a deficient number, since it is larger than the sum of its proper divisors (16639).

21871361 is a wasteful number, since it uses less digits than its factorization.

21871361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16638.

The product of its digits is 2016, while the sum is 29.

The square root of 21871361 is about 4676.6826918233. The cubic root of 21871361 is about 279.6567264353.

The spelling of 21871361 in words is "twenty-one million, eight hundred seventy-one thousand, three hundred sixty-one".