1040399640 has 256 divisors, whose sum is σ = 4014720000. Its totient is φ = 237665664.

The previous prime is 1040399639. The next prime is 1040399653. The reversal of 1040399640 is 469930401.

1040399640 is a `hidden beast` number, since 1 + 0 + 4 + 0 + 3 + 9 + 9 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1040399595 and 1040399604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 611511 + ... + 613209.

It is an arithmetic number, because the mean of its divisors is an integer number (15682500).

Almost surely, 2^1040399640 is an apocalyptic number.

1040399640 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 1040399640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2007360000).

1040399640 is an abundant number, since it is smaller than the sum of its proper divisors (2974320360).

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

1040399640 is an equidigital number, since it uses as much as digits as its factorization.

1040399640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1738 (or 1716 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 1040399640 is about 32255.2265532270. The cubic root of 1040399640 is about 1013.2891625291.

The spelling of 1040399640 in words is "one billion, forty million, three hundred ninety-nine thousand, six hundred forty".