21121144505 has 12 divisors (see below), whose sum is σ = 26923979820. Its totient is φ = 15902978304.

The previous prime is 21121144481. The next prime is 21121144511. The reversal of 21121144505 is 50544112112.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 6583537321 + 14537607184 = 81139^2 + 120572^2 .

It is not a de Polignac number, because 21121144505 - 2²⁰ = 21120095929 is a prime.

It is a super-2 number, since 2×21121144505² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7306910 + ... + 7309799.

It is an arithmetic number, because the mean of its divisors is an integer number (2243664985).

Almost surely, 2^21121144505 is an apocalyptic number.

It is an amenable number.

21121144505 is a deficient number, since it is larger than the sum of its proper divisors (5802835315).

21121144505 is a wasteful number, since it uses less digits than its factorization.

21121144505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14616748 (or 14616731 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 26.

Adding to 21121144505 its reverse (50544112112), we get a palindrome (71665256617).

The spelling of 21121144505 in words is "twenty-one billion, one hundred twenty-one million, one hundred forty-four thousand, five hundred five".