55661440 has 64 divisors (see below), whose sum is σ = 137700000. Its totient is φ = 21489664.

The previous prime is 55661429. The next prime is 55661447. The reversal of 55661440 is 4416655.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55661447) 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, 17061 + ... + 20059.

Almost surely, 2^55661440 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 55661440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68850000).

55661440 is an abundant number, since it is smaller than the sum of its proper divisors (82038560).

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

55661440 is a wasteful number, since it uses less digits than its factorization.

55661440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3047 (or 3035 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 55661440 is about 7460.6594882758. The cubic root of 55661440 is about 381.8136752028.

The spelling of 55661440 in words is "fifty-five million, six hundred sixty-one thousand, four hundred forty".