123638640 has 80 divisors (see below), whose sum is σ = 388585248. Its totient is φ = 32514048.

The previous prime is 123638609. The next prime is 123638653. The reversal of 123638640 is 46836321.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13992 + ... + 21048.

Almost surely, 2^123638640 is an apocalyptic number.

123638640 is a gapful number since it is divisible by the number (10) 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 123638640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (194292624).

123638640 is an abundant number, since it is smaller than the sum of its proper divisors (264946608).

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

123638640 is a wasteful number, since it uses less digits than its factorization.

123638640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7146 (or 7140 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 123638640 is about 11119.2913443259. The cubic root of 123638640 is about 498.1782236569.

The spelling of 123638640 in words is "one hundred twenty-three million, six hundred thirty-eight thousand, six hundred forty".