21771238 has 16 divisors (see below), whose sum is σ = 33868800. Its totient is φ = 10485000.

The previous prime is 21771221. The next prime is 21771247. The reversal of 21771238 is 83217712.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

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, 14863 + ... + 16261.

It is an arithmetic number, because the mean of its divisors is an integer number (2116800).

Almost surely, 2^21771238 is an apocalyptic number.

21771238 is a deficient number, since it is larger than the sum of its proper divisors (12097562).

21771238 is a wasteful number, since it uses less digits than its factorization.

21771238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1683.

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

The square root of 21771238 is about 4665.9659235790. The cubic root of 21771238 is about 279.2293348679.

The spelling of 21771238 in words is "twenty-one million, seven hundred seventy-one thousand, two hundred thirty-eight".