121515550 has 24 divisors (see below), whose sum is σ = 243406296. Its totient is φ = 44867040.

The previous prime is 121515547. The next prime is 121515551. The reversal of 121515550 is 55515121.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121515551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 92824 + ... + 94123.

It is an arithmetic number, because the mean of its divisors is an integer number (10141929).

Almost surely, 2^121515550 is an apocalyptic number.

121515550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

121515550 is an abundant number, since it is smaller than the sum of its proper divisors (121890746).

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

121515550 is a wasteful number, since it uses less digits than its factorization.

121515550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186972 (or 186967 counting only the distinct ones).

The product of its (nonzero) digits is 1250, while the sum is 25.

The square root of 121515550 is about 11023.4091822811. The cubic root of 121515550 is about 495.3102160496.

The spelling of 121515550 in words is "one hundred twenty-one million, five hundred fifteen thousand, five hundred fifty".