81525739 has 4 divisors (see below), whose sum is σ = 81545824. Its totient is φ = 81505656.

The previous prime is 81525701. The next prime is 81525767. The reversal of 81525739 is 93752518.

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

It is a cyclic number.

It is not a de Polignac number, because 81525739 - 2¹³ = 81517547 is a prime.

It is a super-2 number, since 2×81525739² = 13292892238992242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81525779) 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, 1572 + ... + 12865.

It is an arithmetic number, because the mean of its divisors is an integer number (20386456).

Almost surely, 2^81525739 is an apocalyptic number.

81525739 is a deficient number, since it is larger than the sum of its proper divisors (20085).

81525739 is a wasteful number, since it uses less digits than its factorization.

81525739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20084.

The product of its digits is 75600, while the sum is 40.

The square root of 81525739 is about 9029.1604814623. The cubic root of 81525739 is about 433.6089602814.

The spelling of 81525739 in words is "eighty-one million, five hundred twenty-five thousand, seven hundred thirty-nine".