81689377 has 32 divisors (see below), whose sum is σ = 106769664. Its totient is φ = 60652800.

The previous prime is 81689357. The next prime is 81689407. The reversal of 81689377 is 77398618.

It is a cyclic number.

It is not a de Polignac number, because 81689377 - 2¹⁵ = 81656609 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 81689377.

It is not an unprimeable number, because it can be changed into a prime (81689357) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 150727 + ... + 151267.

It is an arithmetic number, because the mean of its divisors is an integer number (3336552).

Almost surely, 2^81689377 is an apocalyptic number.

It is an amenable number.

81689377 is a deficient number, since it is larger than the sum of its proper divisors (25080287).

81689377 is a wasteful number, since it uses less digits than its factorization.

81689377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 649.

The product of its digits is 508032, while the sum is 49.

The square root of 81689377 is about 9038.2175787043. The cubic root of 81689377 is about 433.8988788738.

It can be divided in two parts, 816893 and 77, that multiplied together give a square (62900761 = 7931²).

The spelling of 81689377 in words is "eighty-one million, six hundred eighty-nine thousand, three hundred seventy-seven".