21127971 has 8 divisors (see below), whose sum is σ = 28334160. Its totient is φ = 14003552.

The previous prime is 21127969. The next prime is 21127987. The reversal of 21127971 is 17972112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21127971 - 2¹ = 21127969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21127901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19836 + ... + 20873.

It is an arithmetic number, because the mean of its divisors is an integer number (3541770).

Almost surely, 2^21127971 is an apocalyptic number.

21127971 is a deficient number, since it is larger than the sum of its proper divisors (7206189).

21127971 is a wasteful number, since it uses less digits than its factorization.

21127971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40885.

The product of its digits is 1764, while the sum is 30.

The square root of 21127971 is about 4596.5172685415. The cubic root of 21127971 is about 276.4516994374.

It can be divided in two parts, 211 and 27971, that added together give a palindrome (28182).

The spelling of 21127971 in words is "twenty-one million, one hundred twenty-seven thousand, nine hundred seventy-one".