21665037 has 8 divisors (see below), whose sum is σ = 28927360. Its totient is φ = 14423040.

The previous prime is 21665009. The next prime is 21665041. The reversal of 21665037 is 73056612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21665037 - 2¹¹ = 21662989 is a prime.

It is a super-2 number, since 2×21665037² = 938747656422738, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21664995 and 21665013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665087) 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 in 7 ways as a sum of consecutive naturals, for example, 2389 + ... + 7002.

It is an arithmetic number, because the mean of its divisors is an integer number (3615920).

Almost surely, 2^21665037 is an apocalyptic number.

It is an amenable number.

21665037 is a deficient number, since it is larger than the sum of its proper divisors (7262323).

21665037 is an equidigital number, since it uses as much as digits as its factorization.

21665037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10163.

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 21665037 is about 4654.5716236835. The cubic root of 21665037 is about 278.7745638498.

The spelling of 21665037 in words is "twenty-one million, six hundred sixty-five thousand, thirty-seven".