71505561 has 16 divisors (see below), whose sum is σ = 101813760. Its totient is φ = 44540160.

The previous prime is 71505557. The next prime is 71505583. The reversal of 71505561 is 16550517.

It is not a de Polignac number, because 71505561 - 2² = 71505557 is a prime.

It is a super-2 number, since 2×71505561² = 10226090507849442, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (71505541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10560 + ... + 15953.

It is an arithmetic number, because the mean of its divisors is an integer number (6363360).

Almost surely, 2^71505561 is an apocalyptic number.

It is an amenable number.

71505561 is a deficient number, since it is larger than the sum of its proper divisors (30308199).

71505561 is a wasteful number, since it uses less digits than its factorization.

71505561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26576.

The product of its (nonzero) digits is 5250, while the sum is 30.

The square root of 71505561 is about 8456.0960850738. The cubic root of 71505561 is about 415.0622851306.

The spelling of 71505561 in words is "seventy-one million, five hundred five thousand, five hundred sixty-one".