21121511125151 has 4 divisors (see below), whose sum is σ = 21121660745304. Its totient is φ = 21121361505000.

The previous prime is 21121511125129. The next prime is 21121511125207. The reversal of 21121511125151 is 15152111512112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121511125151 is a prime.

It is a super-2 number, since 2×21121511125151² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121511125051) 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, 74598125 + ... + 74880726.

It is an arithmetic number, because the mean of its divisors is an integer number (5280415186326).

Almost surely, 2^{21121511125151} is an apocalyptic number.

21121511125151 is a deficient number, since it is larger than the sum of its proper divisors (149620153).

21121511125151 is a wasteful number, since it uses less digits than its factorization.

21121511125151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149620152.

The product of its digits is 1000, while the sum is 29.

Adding to 21121511125151 its reverse (15152111512112), we get a palindrome (36273622637263).

The spelling of 21121511125151 in words is "twenty-one trillion, one hundred twenty-one billion, five hundred eleven million, one hundred twenty-five thousand, one hundred fifty-one".