71997840 has 180 divisors, whose sum is σ = 256109724. Its totient is φ = 18123264.

The previous prime is 71997833. The next prime is 71997851. The reversal of 71997840 is 4879917.

It can be written as a sum of positive squares in 2 ways, for example, as 18766224 + 53231616 = 4332^2 + 7296^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 259782 + ... + 260058.

Almost surely, 2^71997840 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 71997840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128054862).

71997840 is an abundant number, since it is smaller than the sum of its proper divisors (184111884).

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

71997840 is a wasteful number, since it uses less digits than its factorization.

71997840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 71997840 is about 8485.1540940633. The cubic root of 71997840 is about 416.0126044011.

The spelling of 71997840 in words is "seventy-one million, nine hundred ninety-seven thousand, eight hundred forty".