21171371 has 4 divisors (see below), whose sum is σ = 22799952. Its totient is φ = 19542792.

The previous prime is 21171361. The next prime is 21171373. The reversal of 21171371 is 17317112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21171371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 814271 + ... + 814296.

It is an arithmetic number, because the mean of its divisors is an integer number (5699988).

Almost surely, 2^21171371 is an apocalyptic number.

21171371 is a deficient number, since it is larger than the sum of its proper divisors (1628581).

21171371 is a wasteful number, since it uses less digits than its factorization.

21171371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1628580.

The product of its digits is 294, while the sum is 23.

The square root of 21171371 is about 4601.2358122574. The cubic root of 21171371 is about 276.6408609663.

Adding to 21171371 its reverse (17317112), we get a palindrome (38488483).

The spelling of 21171371 in words is "twenty-one million, one hundred seventy-one thousand, three hundred seventy-one".