123121540 has 24 divisors (see below), whose sum is σ = 258860952. Its totient is φ = 49190400.

The previous prime is 123121519. The next prime is 123121543. The reversal of 123121540 is 45121321.

It can be written as a sum of positive squares in 4 ways, for example, as 44515584 + 78605956 = 6672^2 + 8866^2 .

It is a super-2 number, since 2×123121540² = 30317827223943200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (123121543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16390 + ... + 22690.

It is an arithmetic number, because the mean of its divisors is an integer number (10785873).

Almost surely, 2^123121540 is an apocalyptic number.

123121540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

123121540 is an abundant number, since it is smaller than the sum of its proper divisors (135739412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

123121540 is a wasteful number, since it uses less digits than its factorization.

123121540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7287 (or 7285 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 123121540 is about 11096.0145998462. The cubic root of 123121540 is about 497.4827346853.

Adding to 123121540 its reverse (45121321), we get a palindrome (168242861).

The spelling of 123121540 in words is "one hundred twenty-three million, one hundred twenty-one thousand, five hundred forty".