20983691 has 4 divisors (see below), whose sum is σ = 21012384. Its totient is φ = 20955000.

The previous prime is 20983681. The next prime is 20983693. The reversal of 20983691 is 19638902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19638902 = 2 ⋅9819451.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20983691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20983693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13220 + ... + 14721.

It is an arithmetic number, because the mean of its divisors is an integer number (5253096).

Almost surely, 2^20983691 is an apocalyptic number.

20983691 is a deficient number, since it is larger than the sum of its proper divisors (28693).

20983691 is an equidigital number, since it uses as much as digits as its factorization.

20983691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28692.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20983691 is about 4580.7958915455. The cubic root of 20983691 is about 275.8209780389.

The spelling of 20983691 in words is "twenty million, nine hundred eighty-three thousand, six hundred ninety-one".