21531121145 has 16 divisors (see below), whose sum is σ = 27036175872. Its totient is φ = 16440900480.

The previous prime is 21531121111. The next prime is 21531121159. The reversal of 21531121145 is 54112113512.

It is not a de Polignac number, because 21531121145 - 2²⁶ = 21464012281 is a prime.

It is a super-2 number, since 2×21531121145² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 940127 + ... + 962756.

It is an arithmetic number, because the mean of its divisors is an integer number (1689760992).

Almost surely, 2^21531121145 is an apocalyptic number.

It is an amenable number.

21531121145 is a deficient number, since it is larger than the sum of its proper divisors (5505054727).

21531121145 is a wasteful number, since it uses less digits than its factorization.

21531121145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1902992.

The product of its digits is 1200, while the sum is 26.

Adding to 21531121145 its reverse (54112113512), we get a palindrome (75643234657).

The spelling of 21531121145 in words is "twenty-one billion, five hundred thirty-one million, one hundred twenty-one thousand, one hundred forty-five".