21537337 has 2 divisors, whose sum is σ = 21537338. Its totient is φ = 21537336.

The previous prime is 21537323. The next prime is 21537349. The reversal of 21537337 is 73373512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12752041 + 8785296 = 3571^2 + 2964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21537337 - 2¹¹ = 21535289 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21537299 and 21537308.

It is not a weakly prime, because it can be changed into another prime (21537137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768668 + 10768669.

It is an arithmetic number, because the mean of its divisors is an integer number (10768669).

Almost surely, 2^21537337 is an apocalyptic number.

It is an amenable number.

21537337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21537337 is an equidigital number, since it uses as much as digits as its factorization.

21537337 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13230, while the sum is 31.

The square root of 21537337 is about 4640.8336535584. The cubic root of 21537337 is about 278.2257581657.

The spelling of 21537337 in words is "twenty-one million, five hundred thirty-seven thousand, three hundred thirty-seven".