21871893 has 4 divisors (see below), whose sum is σ = 29162528. Its totient is φ = 14581260.

The previous prime is 21871849. The next prime is 21871903. The reversal of 21871893 is 39817812.

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 not a de Polignac number, because 21871893 - 2¹⁰ = 21870869 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871393) 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, 3645313 + ... + 3645318.

It is an arithmetic number, because the mean of its divisors is an integer number (7290632).

Almost surely, 2^21871893 is an apocalyptic number.

It is an amenable number.

21871893 is a deficient number, since it is larger than the sum of its proper divisors (7290635).

21871893 is an equidigital number, since it uses as much as digits as its factorization.

21871893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7290634.

The product of its digits is 24192, while the sum is 39.

The square root of 21871893 is about 4676.7395694009. The cubic root of 21871893 is about 279.6589938780.

The spelling of 21871893 in words is "twenty-one million, eight hundred seventy-one thousand, eight hundred ninety-three".