81391652 has 12 divisors (see below), whose sum is σ = 142886940. Its totient is φ = 40566816.

The previous prime is 81391619. The next prime is 81391669. The reversal of 81391652 is 25619318.

It can be written as a sum of positive squares in 2 ways, for example, as 26275876 + 55115776 = 5126^2 + 7424^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30827 + ... + 33362.

It is an arithmetic number, because the mean of its divisors is an integer number (11907245).

Almost surely, 2^81391652 is an apocalyptic number.

It is an amenable number.

81391652 is a deficient number, since it is larger than the sum of its proper divisors (61495288).

81391652 is a wasteful number, since it uses less digits than its factorization.

81391652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64510 (or 64508 counting only the distinct ones).

The product of its digits is 12960, while the sum is 35.

The square root of 81391652 is about 9021.7322061786. The cubic root of 81391652 is about 433.3711080811.

The spelling of 81391652 in words is "eighty-one million, three hundred ninety-one thousand, six hundred fifty-two".