21660037 has 4 divisors (see below), whose sum is σ = 24754336. Its totient is φ = 18565740.

The previous prime is 21660011. The next prime is 21660047. The reversal of 21660037 is 73006612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21660037 - 2²³ = 13271429 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21659993 and 21660020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1547139 + ... + 1547152.

It is an arithmetic number, because the mean of its divisors is an integer number (6188584).

Almost surely, 2^21660037 is an apocalyptic number.

It is an amenable number.

21660037 is a deficient number, since it is larger than the sum of its proper divisors (3094299).

21660037 is an equidigital number, since it uses as much as digits as its factorization.

21660037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3094298.

The product of its (nonzero) digits is 1512, while the sum is 25.

The square root of 21660037 is about 4654.0344863355. The cubic root of 21660037 is about 278.7531163895.

Adding to 21660037 its reverse (73006612), we get a palindrome (94666649).

The spelling of 21660037 in words is "twenty-one million, six hundred sixty thousand, thirty-seven".