66138240 has 384 divisors, whose sum is σ = 265118400. Its totient is φ = 13934592.

The previous prime is 66138239. The next prime is 66138251. The reversal of 66138240 is 4283166.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 66138198 and 66138207.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1787502 + ... + 1787538.

Almost surely, 2^66138240 is an apocalyptic number.

66138240 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66138240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132559200).

66138240 is an abundant number, since it is smaller than the sum of its proper divisors (198980160).

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

66138240 is a wasteful number, since it uses less digits than its factorization.

66138240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 66138240 is about 8132.5420380100. The cubic root of 66138240 is about 404.4059573282.

The spelling of 66138240 in words is "sixty-six million, one hundred thirty-eight thousand, two hundred forty".