81601907 has 4 divisors (see below), whose sum is σ = 85149840. Its totient is φ = 78053976.

The previous prime is 81601901. The next prime is 81601937. The reversal of 81601907 is 70910618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 70910618 = 2 ⋅35455309.

It is a cyclic number.

It is not a de Polignac number, because 81601907 - 2⁶ = 81601843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81601901) 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, 1773932 + ... + 1773977.

It is an arithmetic number, because the mean of its divisors is an integer number (21287460).

Almost surely, 2^81601907 is an apocalyptic number.

81601907 is a deficient number, since it is larger than the sum of its proper divisors (3547933).

81601907 is a wasteful number, since it uses less digits than its factorization.

81601907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3547932.

The product of its (nonzero) digits is 3024, while the sum is 32.

The square root of 81601907 is about 9033.3773861164. The cubic root of 81601907 is about 433.7439558770.

The spelling of 81601907 in words is "eighty-one million, six hundred one thousand, nine hundred seven".