121555540 has 24 divisors (see below), whose sum is σ = 268702560. Its totient is φ = 46063008.

The previous prime is 121555537. The next prime is 121555547. The reversal of 121555540 is 45555121.

It is a junction number, because it is equal to n+sod(n) for n = 121555499 and 121555508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121555547) 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, 159562 + ... + 160321.

It is an arithmetic number, because the mean of its divisors is an integer number (11195940).

Almost surely, 2^121555540 is an apocalyptic number.

121555540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

121555540 is an abundant number, since it is smaller than the sum of its proper divisors (147147020).

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

121555540 is a wasteful number, since it uses less digits than its factorization.

121555540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319911 (or 319909 counting only the distinct ones).

The product of its (nonzero) digits is 5000, while the sum is 28.

The square root of 121555540 is about 11025.2229002411. Note that the first 3 decimals coincide. The cubic root of 121555540 is about 495.3645445782.

The spelling of 121555540 in words is "one hundred twenty-one million, five hundred fifty-five thousand, five hundred forty".