21542263 has 2 divisors, whose sum is σ = 21542264. Its totient is φ = 21542262.

The previous prime is 21542233. The next prime is 21542299. The reversal of 21542263 is 36224512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21542263 - 2⁵ = 21542231 is a prime.

It is a super-2 number, since 2×21542263² = 928138190322338, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771131 + 10771132.

It is an arithmetic number, because the mean of its divisors is an integer number (10771132).

Almost surely, 2^21542263 is an apocalyptic number.

21542263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542263 is an equidigital number, since it uses as much as digits as its factorization.

21542263 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 25.

The square root of 21542263 is about 4641.3643468273. The cubic root of 21542263 is about 278.2469683956.

Adding to 21542263 its reverse (36224512), we get a palindrome (57766775).

The spelling of 21542263 in words is "twenty-one million, five hundred forty-two thousand, two hundred sixty-three".