21666365437 has 8 divisors (see below), whose sum is σ = 22826200160. Its totient is φ = 20508480720.

The previous prime is 21666365407. The next prime is 21666365449. The reversal of 21666365437 is 73456366612.

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

It is a cyclic number.

It is not a de Polignac number, because 21666365437 - 2¹⁹ = 21665841149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666365407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 464658 + ... + 509155.

It is an arithmetic number, because the mean of its divisors is an integer number (2853275020).

Almost surely, 2^21666365437 is an apocalyptic number.

It is an amenable number.

21666365437 is a deficient number, since it is larger than the sum of its proper divisors (1159834723).

21666365437 is a wasteful number, since it uses less digits than its factorization.

21666365437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 975003.

The product of its digits is 3265920, while the sum is 49.

The spelling of 21666365437 in words is "twenty-one billion, six hundred sixty-six million, three hundred sixty-five thousand, four hundred thirty-seven".