213497681821 has 4 divisors (see below), whose sum is σ = 213577856352. Its totient is φ = 213417507292.

The previous prime is 213497681819. The next prime is 213497681849. The reversal of 213497681821 is 128186794312.

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 213497681821 - 2¹ = 213497681819 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 (213497681801) 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, 40083271 + ... + 40088596.

It is an arithmetic number, because the mean of its divisors is an integer number (53394464088).

Almost surely, 2^213497681821 is an apocalyptic number.

It is an amenable number.

213497681821 is a deficient number, since it is larger than the sum of its proper divisors (80174531).

213497681821 is an equidigital number, since it uses as much as digits as its factorization.

213497681821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80174530.

The product of its digits is 1161216, while the sum is 52.

The spelling of 213497681821 in words is "two hundred thirteen billion, four hundred ninety-seven million, six hundred eighty-one thousand, eight hundred twenty-one".