21539467 has 2 divisors, whose sum is σ = 21539468. Its totient is φ = 21539466.

The previous prime is 21539449. The next prime is 21539471. The reversal of 21539467 is 76493512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21539467 - 2²³ = 13150859 is a prime.

It is not a weakly prime, because it can be changed into another prime (21539417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10769733 + 10769734.

It is an arithmetic number, because the mean of its divisors is an integer number (10769734).

Almost surely, 2^21539467 is an apocalyptic number.

21539467 is a deficient number, since it is larger than the sum of its proper divisors (1).

21539467 is an equidigital number, since it uses as much as digits as its factorization.

21539467 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 37.

The square root of 21539467 is about 4641.0631325161. The cubic root of 21539467 is about 278.2349298556.

The spelling of 21539467 in words is "twenty-one million, five hundred thirty-nine thousand, four hundred sixty-seven".