55121240 has 16 divisors (see below), whose sum is σ = 124022880. Its totient is φ = 22048480.

The previous prime is 55121239. The next prime is 55121243. The reversal of 55121240 is 4212155.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55121243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 688976 + ... + 689055.

It is an arithmetic number, because the mean of its divisors is an integer number (7751430).

Almost surely, 2^55121240 is an apocalyptic number.

It is an amenable number.

55121240 is an abundant number, since it is smaller than the sum of its proper divisors (68901640).

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

55121240 is a wasteful number, since it uses less digits than its factorization.

55121240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1378042 (or 1378038 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 55121240 is about 7424.3679865696. The cubic root of 55121240 is about 380.5744773380.

Adding to 55121240 its reverse (4212155), we get a palindrome (59333395).

The spelling of 55121240 in words is "fifty-five million, one hundred twenty-one thousand, two hundred forty".