72320040 has 320 divisors, whose sum is σ = 279916560. Its totient is φ = 16588800.

The previous prime is 72320033. The next prime is 72320047. The reversal of 72320040 is 4002327.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (72320033) and next prime (72320047).

It can be written as a sum of positive squares in 8 ways, for example, as 48525156 + 23794884 = 6966^2 + 4878^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 72319995 and 72320022.

It is not an unprimeable number, because it can be changed into a prime (72320047) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 715990 + ... + 716090.

Almost surely, 2^72320040 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 72320040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139958280).

72320040 is an abundant number, since it is smaller than the sum of its proper divisors (207596520).

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

72320040 is a wasteful number, since it uses less digits than its factorization.

72320040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 18.

The square root of 72320040 is about 8504.1190019896. The cubic root of 72320040 is about 416.6322517353.

Adding to 72320040 its reverse (4002327), we get a palindrome (76322367).

The spelling of 72320040 in words is "seventy-two million, three hundred twenty thousand, forty".