81532649 has 4 divisors (see below), whose sum is σ = 88944720. Its totient is φ = 74120580.

The previous prime is 81532621. The next prime is 81532669. The reversal of 81532649 is 94623518.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81532649 - 2⁸ = 81532393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81532669) 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, 3706019 + ... + 3706040.

It is an arithmetic number, because the mean of its divisors is an integer number (22236180).

Almost surely, 2^81532649 is an apocalyptic number.

It is an amenable number.

81532649 is a deficient number, since it is larger than the sum of its proper divisors (7412071).

81532649 is a wasteful number, since it uses less digits than its factorization.

81532649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7412070.

The product of its digits is 51840, while the sum is 38.

The square root of 81532649 is about 9029.5431224398. The cubic root of 81532649 is about 433.6212106181.

The spelling of 81532649 in words is "eighty-one million, five hundred thirty-two thousand, six hundred forty-nine".