213121012121 has 4 divisors (see below), whose sum is σ = 213145430544. Its totient is φ = 213096593700.

The previous prime is 213121012109. The next prime is 213121012127. The reversal of 213121012121 is 121210121312.

It is a happy number.

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 213121012121 - 2¹⁸ = 213120749977 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 213121012121.

It is not an unprimeable number, because it can be changed into a prime (213121012127) 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, 12196115 + ... + 12213576.

It is an arithmetic number, because the mean of its divisors is an integer number (53286357636).

Almost surely, 2^213121012121 is an apocalyptic number.

It is an amenable number.

213121012121 is a deficient number, since it is larger than the sum of its proper divisors (24418423).

213121012121 is an equidigital number, since it uses as much as digits as its factorization.

213121012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24418422.

The product of its (nonzero) digits is 48, while the sum is 17.

Adding to 213121012121 its reverse (121210121312), we get a palindrome (334331133433).

The spelling of 213121012121 in words is "two hundred thirteen billion, one hundred twenty-one million, twelve thousand, one hundred twenty-one".