21542071 has 2 divisors, whose sum is σ = 21542072. Its totient is φ = 21542070.

The previous prime is 21542063. The next prime is 21542083. The reversal of 21542071 is 17024512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21542071 - 2³ = 21542063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771035 + 10771036.

It is an arithmetic number, because the mean of its divisors is an integer number (10771036).

Almost surely, 2^21542071 is an apocalyptic number.

21542071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542071 is an equidigital number, since it uses as much as digits as its factorization.

21542071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21542071 is about 4641.3436632079. The cubic root of 21542071 is about 278.2461417480.

Adding to 21542071 its reverse (17024512), we get a palindrome (38566583).

It can be divided in two parts, 2154 and 2071, that added together give a square (4225 = 65²).

The spelling of 21542071 in words is "twenty-one million, five hundred forty-two thousand, seventy-one".