57781638 has 12 divisors (see below), whose sum is σ = 125193588. Its totient is φ = 19260540.

The previous prime is 57781631. The next prime is 57781643. The reversal of 57781638 is 83618775.

57781638 is a `hidden beast` number, since 5 + 7 + 7 + 8 + 1 + 638 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 57781593 and 57781602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (57781631) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1605028 + ... + 1605063.

It is an arithmetic number, because the mean of its divisors is an integer number (10432799).

Almost surely, 2^57781638 is an apocalyptic number.

57781638 is an abundant number, since it is smaller than the sum of its proper divisors (67411950).

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

57781638 is a wasteful number, since it uses less digits than its factorization.

57781638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3210099 (or 3210096 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 57781638 is about 7601.4234193340. The cubic root of 57781638 is about 386.6012759351.

It can be divided in two parts, 577 and 81638, that added together give a triangular number (82215 = T₄₀₅).

The spelling of 57781638 in words is "fifty-seven million, seven hundred eighty-one thousand, six hundred thirty-eight".