213521994921 has 4 divisors (see below), whose sum is σ = 284695993232. Its totient is φ = 142347996612.

The previous prime is 213521994887. The next prime is 213521994929. The reversal of 213521994921 is 129499125312.

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 not a de Polignac number, because 213521994921 - 2¹³ = 213521986729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (213521994929) 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, 35586999151 + ... + 35586999156.

It is an arithmetic number, because the mean of its divisors is an integer number (71173998308).

Almost surely, 2^213521994921 is an apocalyptic number.

It is an amenable number.

213521994921 is a deficient number, since it is larger than the sum of its proper divisors (71173998311).

213521994921 is an equidigital number, since it uses as much as digits as its factorization.

213521994921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71173998310.

The product of its digits is 349920, while the sum is 48.

The spelling of 213521994921 in words is "two hundred thirteen billion, five hundred twenty-one million, nine hundred ninety-four thousand, nine hundred twenty-one".