71661240 has 128 divisors (see below), whose sum is σ = 273024000. Its totient is φ = 16377984.

The previous prime is 71661209. The next prime is 71661241. The reversal of 71661240 is 4216617.

71661240 is a `hidden beast` number, since 7 + 1 + 6 + 612 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71661241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2821 + ... + 12299.

It is an arithmetic number, because the mean of its divisors is an integer number (2133000).

Almost surely, 2^71661240 is an apocalyptic number.

71661240 is a gapful number since it is divisible by the number (70) 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 71661240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136512000).

71661240 is an abundant number, since it is smaller than the sum of its proper divisors (201362760).

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

71661240 is a wasteful number, since it uses less digits than its factorization.

71661240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9506 (or 9496 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 71661240 is about 8465.2962145456. The cubic root of 71661240 is about 415.3632857044.

Adding to 71661240 its reverse (4216617), we get a palindrome (75877857).

The spelling of 71661240 in words is "seventy-one million, six hundred sixty-one thousand, two hundred forty".