21011021113121 has 4 divisors (see below), whose sum is σ = 22627253506452. Its totient is φ = 19394788719792.

The previous prime is 21011021113057. The next prime is 21011021113153. The reversal of 21011021113121 is 12131112011012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1901533439521 + 19109487673600 = 1378961^2 + 4371440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011021113121 - 2⁶ = 21011021113057 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 21011021113121.

It is not an unprimeable number, because it can be changed into a prime (21011021113721) 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, 808116196646 + ... + 808116196671.

It is an arithmetic number, because the mean of its divisors is an integer number (5656813376613).

Almost surely, 2^{21011021113121} is an apocalyptic number.

It is an amenable number.

21011021113121 is a deficient number, since it is larger than the sum of its proper divisors (1616232393331).

21011021113121 is a wasteful number, since it uses less digits than its factorization.

21011021113121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1616232393330.

The product of its (nonzero) digits is 24, while the sum is 17.

Adding to 21011021113121 its reverse (12131112011012), we get a palindrome (33142133124133).

The spelling of 21011021113121 in words is "twenty-one trillion, eleven billion, twenty-one million, one hundred thirteen thousand, one hundred twenty-one".