55131440 has 80 divisors (see below), whose sum is σ = 157781568. Its totient is φ = 17445888.

The previous prime is 55131409. The next prime is 55131449. The reversal of 55131440 is 4413155.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (55131449) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3494 + ... + 11066.

Almost surely, 2^55131440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 55131440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78890784).

55131440 is an abundant number, since it is smaller than the sum of its proper divisors (102650128).

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

55131440 is a wasteful number, since it uses less digits than its factorization.

55131440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7606 (or 7600 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 55131440 is about 7425.0548819521. The cubic root of 55131440 is about 380.5979505657.

Adding to 55131440 its reverse (4413155), we get a palindrome (59544595).

The spelling of 55131440 in words is "fifty-five million, one hundred thirty-one thousand, four hundred forty".