21871372 has 18 divisors (see below), whose sum is σ = 38688468. Its totient is φ = 10818648.

The previous prime is 21871331. The next prime is 21871379. The reversal of 21871372 is 27317812.

It is not an unprimeable number, because it can be changed into a prime (21871379) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 77143 + ... + 77425.

Almost surely, 2^21871372 is an apocalyptic number.

It is an amenable number.

21871372 is a deficient number, since it is larger than the sum of its proper divisors (16817096).

21871372 is a wasteful number, since it uses less digits than its factorization.

21871372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 565 (or 424 counting only the distinct ones).

The product of its digits is 4704, while the sum is 31.

The square root of 21871372 is about 4676.6838678705. The cubic root of 21871372 is about 279.6567733189.

The spelling of 21871372 in words is "twenty-one million, eight hundred seventy-one thousand, three hundred seventy-two".