20081691 has 24 divisors (see below), whose sum is σ = 34594560. Its totient is φ = 10975536.

The previous prime is 20081681. The next prime is 20081741. The reversal of 20081691 is 19618002.

It is not a de Polignac number, because 20081691 - 2¹⁰ = 20080667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20081671) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5481 + ... + 8378.

It is an arithmetic number, because the mean of its divisors is an integer number (1441440).

Almost surely, 2^20081691 is an apocalyptic number.

20081691 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20081691 is a deficient number, since it is larger than the sum of its proper divisors (14512869).

20081691 is a wasteful number, since it uses less digits than its factorization.

20081691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13895 (or 13892 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 20081691 is about 4481.2599790684. The cubic root of 20081691 is about 271.8108321016.

Adding to 20081691 its reverse (19618002), we get a palindrome (39699693).

The spelling of 20081691 in words is "twenty million, eighty-one thousand, six hundred ninety-one".