81607501 has 4 divisors (see below), whose sum is σ = 82127452. Its totient is φ = 81087552.

The previous prime is 81607499. The next prime is 81607511. The reversal of 81607501 is 10570618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10570618 = 2 ⋅5285309.

It can be written as a sum of positive squares in 2 ways, for example, as 8094025 + 73513476 = 2845^2 + 8574^2 .

It is a cyclic number.

It is not a de Polignac number, because 81607501 - 2¹ = 81607499 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81607501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81607511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259740 + ... + 260053.

It is an arithmetic number, because the mean of its divisors is an integer number (20531863).

Almost surely, 2^81607501 is an apocalyptic number.

It is an amenable number.

81607501 is a deficient number, since it is larger than the sum of its proper divisors (519951).

81607501 is a wasteful number, since it uses less digits than its factorization.

81607501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 519950.

The product of its (nonzero) digits is 1680, while the sum is 28.

The square root of 81607501 is about 9033.6870102965. The cubic root of 81607501 is about 433.7538670353.

The spelling of 81607501 in words is "eighty-one million, six hundred seven thousand, five hundred one".