21142271 has 4 divisors (see below), whose sum is σ = 22385952. Its totient is φ = 19898592.

The previous prime is 21142259. The next prime is 21142273. The reversal of 21142271 is 17224112.

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

It is a cyclic number.

It is not a de Polignac number, because 21142271 - 2¹⁴ = 21125887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21142273) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 621815 + ... + 621848.

It is an arithmetic number, because the mean of its divisors is an integer number (5596488).

Almost surely, 2^21142271 is an apocalyptic number.

21142271 is a deficient number, since it is larger than the sum of its proper divisors (1243681).

21142271 is a wasteful number, since it uses less digits than its factorization.

21142271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1243680.

The product of its digits is 224, while the sum is 20.

The square root of 21142271 is about 4598.0725309634. The cubic root of 21142271 is about 276.5140554447.

Adding to 21142271 its reverse (17224112), we get a palindrome (38366383).

The spelling of 21142271 in words is "twenty-one million, one hundred forty-two thousand, two hundred seventy-one".