71521840 has 40 divisors (see below), whose sum is σ = 179082288. Its totient is φ = 26407680.

The previous prime is 71521799. The next prime is 71521843. The reversal of 71521840 is 4812517.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 71521799 and 71521808.

It is not an unprimeable number, because it can be changed into a prime (71521843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33346 + ... + 35425.

Almost surely, 2^71521840 is an apocalyptic number.

It is an amenable number.

71521840 is an abundant number, since it is smaller than the sum of its proper divisors (107560448).

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

71521840 is a wasteful number, since it uses less digits than its factorization.

71521840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68797 (or 68791 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 71521840 is about 8457.0585903138. The cubic root of 71521840 is about 415.0937805190.

It can be divided in two parts, 71521 and 840, that added together give a square (72361 = 269²).

The spelling of 71521840 in words is "seventy-one million, five hundred twenty-one thousand, eight hundred forty".