20866633537 has 4 divisors (see below), whose sum is σ = 21160529856. Its totient is φ = 20572737220.

The previous prime is 20866633507. The next prime is 20866633547. The reversal of 20866633537 is 73533666802.

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, and also an emirpimes, since its reverse is a distinct semiprime: 73533666802 = 2 ⋅36766833401.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20866633537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20866633507) 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, 146948053 + ... + 146948194.

It is an arithmetic number, because the mean of its divisors is an integer number (5290132464).

Almost surely, 2^20866633537 is an apocalyptic number.

It is an amenable number.

20866633537 is a deficient number, since it is larger than the sum of its proper divisors (293896319).

20866633537 is an equidigital number, since it uses as much as digits as its factorization.

20866633537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293896318.

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

The spelling of 20866633537 in words is "twenty billion, eight hundred sixty-six million, six hundred thirty-three thousand, five hundred thirty-seven".