21871390 has 16 divisors (see below), whose sum is σ = 41080608. Its totient is φ = 8368096.

The previous prime is 21871379. The next prime is 21871393. The reversal of 21871390 is 9317812.

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 7 ways as a sum of consecutive naturals, for example, 47317 + ... + 47776.

It is an arithmetic number, because the mean of its divisors is an integer number (2567538).

Almost surely, 2^21871390 is an apocalyptic number.

21871390 is a deficient number, since it is larger than the sum of its proper divisors (19209218).

21871390 is a wasteful number, since it uses less digits than its factorization.

21871390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95123.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21871390 is about 4676.6857923106. The cubic root of 21871390 is about 279.6568500375.

The spelling of 21871390 in words is "twenty-one million, eight hundred seventy-one thousand, three hundred ninety".