71281920 has 144 divisors (see below), whose sum is σ = 239883840. Its totient is φ = 17989632.

The previous prime is 71281909. The next prime is 71281921. The reversal of 71281920 is 2918217.

It is a super-2 number, since 2×71281920² = 10162224237772800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71281921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72472 + ... + 73448.

It is an arithmetic number, because the mean of its divisors is an integer number (1665860).

Almost surely, 2^71281920 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 71281920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119941920).

71281920 is an abundant number, since it is smaller than the sum of its proper divisors (168601920).

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

71281920 is a wasteful number, since it uses less digits than its factorization.

71281920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020 (or 1006 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 71281920 is about 8442.8620739652. The cubic root of 71281920 is about 414.6291165542.

The spelling of 71281920 in words is "seventy-one million, two hundred eighty-one thousand, nine hundred twenty".