21542771 has 2 divisors, whose sum is σ = 21542772. Its totient is φ = 21542770.

The previous prime is 21542767. The next prime is 21542777. The reversal of 21542771 is 17724512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21542771 - 2² = 21542767 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21542777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771385 + 10771386.

It is an arithmetic number, because the mean of its divisors is an integer number (10771386).

Almost surely, 2^21542771 is an apocalyptic number.

21542771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542771 is an equidigital number, since it uses as much as digits as its factorization.

21542771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3920, while the sum is 29.

The square root of 21542771 is about 4641.4190717926. The cubic root of 21542771 is about 278.2491555435.

The spelling of 21542771 in words is "twenty-one million, five hundred forty-two thousand, seven hundred seventy-one".