21736537 has 2 divisors, whose sum is σ = 21736538. Its totient is φ = 21736536.

The previous prime is 21736529. The next prime is 21736577. The reversal of 21736537 is 73563712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16451136 + 5285401 = 4056^2 + 2299^2 .

It is a cyclic number.

It is not a de Polignac number, because 21736537 - 2³ = 21736529 is a prime.

It is not a weakly prime, because it can be changed into another prime (21736577) 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, 10868268 + 10868269.

It is an arithmetic number, because the mean of its divisors is an integer number (10868269).

Almost surely, 2^21736537 is an apocalyptic number.

It is an amenable number.

21736537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21736537 is an equidigital number, since it uses as much as digits as its factorization.

21736537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26460, while the sum is 34.

The square root of 21736537 is about 4662.2459180099. The cubic root of 21736537 is about 279.0809021859.

The spelling of 21736537 in words is "twenty-one million, seven hundred thirty-six thousand, five hundred thirty-seven".