21181812037 has 4 divisors (see below), whose sum is σ = 21449936320. Its totient is φ = 20913687756.

The previous prime is 21181812013. The next prime is 21181812049. The reversal of 21181812037 is 73021818112.

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 a de Polignac number, because none of the positive numbers 2^k-21181812037 is a prime.

It is a super-2 number, since 2×21181812037² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21181811993 and 21181812011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21181812097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134062023 + ... + 134062180.

It is an arithmetic number, because the mean of its divisors is an integer number (5362484080).

Almost surely, 2^21181812037 is an apocalyptic number.

It is an amenable number.

21181812037 is a deficient number, since it is larger than the sum of its proper divisors (268124283).

21181812037 is an equidigital number, since it uses as much as digits as its factorization.

21181812037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268124282.

The product of its (nonzero) digits is 5376, while the sum is 34.

The spelling of 21181812037 in words is "twenty-one billion, one hundred eighty-one million, eight hundred twelve thousand, thirty-seven".