21537073 has 2 divisors, whose sum is σ = 21537074. Its totient is φ = 21537072.

The previous prime is 21537049. The next prime is 21537091. The reversal of 21537073 is 37073512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20502784 + 1034289 = 4528^2 + 1017^2 .

It is a cyclic number.

It is not a de Polignac number, because 21537073 - 2⁹ = 21536561 is a prime.

It is not a weakly prime, because it can be changed into another prime (21537473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768536 + 10768537.

It is an arithmetic number, because the mean of its divisors is an integer number (10768537).

Almost surely, 2^21537073 is an apocalyptic number.

It is an amenable number.

21537073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21537073 is an equidigital number, since it uses as much as digits as its factorization.

21537073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4410, while the sum is 28.

The square root of 21537073 is about 4640.8052103056. The cubic root of 21537073 is about 278.2246213507.

The spelling of 21537073 in words is "twenty-one million, five hundred thirty-seven thousand, seventy-three".