20691493 has 4 divisors (see below), whose sum is σ = 20759200. Its totient is φ = 20623788.

The previous prime is 20691479. The next prime is 20691497. The reversal of 20691493 is 39419602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20691493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20691497) 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, 33393 + ... + 34006.

It is an arithmetic number, because the mean of its divisors is an integer number (5189800).

Almost surely, 2^20691493 is an apocalyptic number.

It is an amenable number.

20691493 is a deficient number, since it is larger than the sum of its proper divisors (67707).

20691493 is an equidigital number, since it uses as much as digits as its factorization.

20691493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67706.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 20691493 is about 4548.7902787444. The cubic root of 20691493 is about 274.5347195586.

The spelling of 20691493 in words is "twenty million, six hundred ninety-one thousand, four hundred ninety-three".