21156771 has 8 divisors (see below), whose sum is σ = 28310544. Its totient is φ = 14053760.

The previous prime is 21156769. The next prime is 21156809. The reversal of 21156771 is 17765112.

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 21156771 - 2¹ = 21156769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21156701) 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, 11706 + ... + 13391.

It is an arithmetic number, because the mean of its divisors is an integer number (3538818).

Almost surely, 2^21156771 is an apocalyptic number.

21156771 is a deficient number, since it is larger than the sum of its proper divisors (7153773).

21156771 is a wasteful number, since it uses less digits than its factorization.

21156771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25381.

The product of its digits is 2940, while the sum is 30.

The square root of 21156771 is about 4599.6490083484. The cubic root of 21156771 is about 276.5772548609.

The spelling of 21156771 in words is "twenty-one million, one hundred fifty-six thousand, seven hundred seventy-one".