18291820212121 has 4 divisors (see below), whose sum is σ = 18291835072512. Its totient is φ = 18291805351732.

The previous prime is 18291820212119. The next prime is 18291820212163. The reversal of 18291820212121 is 12121202819281.

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 18291820212121 - 2¹ = 18291820212119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18291820215121) 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, 5398681 + ... + 8107366.

It is an arithmetic number, because the mean of its divisors is an integer number (4572958768128).

Almost surely, 2^{18291820212121} is an apocalyptic number.

It is an amenable number.

18291820212121 is a deficient number, since it is larger than the sum of its proper divisors (14860391).

18291820212121 is a wasteful number, since it uses less digits than its factorization.

18291820212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14860390.

The product of its (nonzero) digits is 18432, while the sum is 40.

The spelling of 18291820212121 in words is "eighteen trillion, two hundred ninety-one billion, eight hundred twenty million, two hundred twelve thousand, one hundred twenty-one".