21571438 has 16 divisors (see below), whose sum is σ = 37048320. Its totient is φ = 9227736.

The previous prime is 21571421. The next prime is 21571439. The reversal of 21571438 is 83417512.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571439) 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 7 ways as a sum of consecutive naturals, for example, 8995 + ... + 11137.

It is an arithmetic number, because the mean of its divisors is an integer number (2315520).

Almost surely, 2^21571438 is an apocalyptic number.

21571438 is a deficient number, since it is larger than the sum of its proper divisors (15476882).

21571438 is a wasteful number, since it uses less digits than its factorization.

21571438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2871.

The product of its digits is 6720, while the sum is 31.

The square root of 21571438 is about 4644.5062170267. The cubic root of 21571438 is about 278.3725230374.

The spelling of 21571438 in words is "twenty-one million, five hundred seventy-one thousand, four hundred thirty-eight".