71021720 has 64 divisors (see below), whose sum is σ = 199238400. Its totient is φ = 22135680.

The previous prime is 71021719. The next prime is 71021729. The reversal of 71021720 is 2712017.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 71021692 and 71021701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71021729) 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 15 ways as a sum of consecutive naturals, for example, 8450 + ... + 14609.

It is an arithmetic number, because the mean of its divisors is an integer number (3113100).

Almost surely, 2^71021720 is an apocalyptic number.

71021720 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

71021720 is an abundant number, since it is smaller than the sum of its proper divisors (128216680).

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

71021720 is a wasteful number, since it uses less digits than its factorization.

71021720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23088 (or 23084 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 71021720 is about 8427.4385195028. The cubic root of 71021720 is about 414.1239953141.

Adding to 71021720 its reverse (2712017), we get a palindrome (73733737).

The spelling of 71021720 in words is "seventy-one million, twenty-one thousand, seven hundred twenty".