20697191 has 4 divisors (see below), whose sum is σ = 20720400. Its totient is φ = 20673984.

The previous prime is 20697167. The next prime is 20697199. The reversal of 20697191 is 19179602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20697191 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 (20697199) 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, 10211 + ... + 12068.

It is an arithmetic number, because the mean of its divisors is an integer number (5180100).

Almost surely, 2^20697191 is an apocalyptic number.

20697191 is a deficient number, since it is larger than the sum of its proper divisors (23209).

20697191 is an equidigital number, since it uses as much as digits as its factorization.

20697191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23208.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 20697191 is about 4549.4165559992. The cubic root of 20697191 is about 274.5599175996.

The spelling of 20697191 in words is "twenty million, six hundred ninety-seven thousand, one hundred ninety-one".