71507921 has 4 divisors (see below), whose sum is σ = 72680244. Its totient is φ = 70335600.

The previous prime is 71507873. The next prime is 71507923. The reversal of 71507921 is 12970517.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11662225 + 59845696 = 3415^2 + 7736^2 .

It is a cyclic number.

It is not a de Polignac number, because 71507921 - 2¹⁸ = 71245777 is a prime.

It is a super-2 number, since 2×71507921² = 10226765531484482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71507923) 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 3 ways as a sum of consecutive naturals, for example, 586070 + ... + 586191.

It is an arithmetic number, because the mean of its divisors is an integer number (18170061).

Almost surely, 2^71507921 is an apocalyptic number.

It is an amenable number.

71507921 is a deficient number, since it is larger than the sum of its proper divisors (1172323).

71507921 is a wasteful number, since it uses less digits than its factorization.

71507921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1172322.

The product of its (nonzero) digits is 4410, while the sum is 32.

The square root of 71507921 is about 8456.2356282213. The cubic root of 71507921 is about 415.0668513779.

The spelling of 71507921 in words is "seventy-one million, five hundred seven thousand, nine hundred twenty-one".