72991440 has 60 divisors (see below), whose sum is σ = 245132004. Its totient is φ = 19464192.

The previous prime is 72991427. The next prime is 72991447. The reversal of 72991440 is 4419927.

It can be written as a sum of positive squares in 2 ways, for example, as 50637456 + 22353984 = 7116^2 + 4728^2 .

It is a tau number, because it is divible by the number of its divisors (60).

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 = 72991395 and 72991404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72991447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49969 + ... + 51408.

Almost surely, 2^72991440 is an apocalyptic number.

It is an amenable number.

72991440 is an abundant number, since it is smaller than the sum of its proper divisors (172140564).

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

72991440 is a wasteful number, since it uses less digits than its factorization.

72991440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101396 (or 101387 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 72991440 is about 8543.5027945217. The cubic root of 72991440 is about 417.9175833176.

The spelling of 72991440 in words is "seventy-two million, nine hundred ninety-one thousand, four hundred forty".