20591691 has 4 divisors (see below), whose sum is σ = 27455592. Its totient is φ = 13727792.

The previous prime is 20591689. The next prime is 20591707. The reversal of 20591691 is 19619502.

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

It is a cyclic number.

It is not a de Polignac number, because 20591691 - 2¹ = 20591689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20591191) 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, 3431946 + ... + 3431951.

It is an arithmetic number, because the mean of its divisors is an integer number (6863898).

Almost surely, 2^20591691 is an apocalyptic number.

20591691 is a deficient number, since it is larger than the sum of its proper divisors (6863901).

20591691 is an equidigital number, since it uses as much as digits as its factorization.

20591691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6863900.

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 20591691 is about 4537.8068491288. The cubic root of 20591691 is about 274.0926170288.

The spelling of 20591691 in words is "twenty million, five hundred ninety-one thousand, six hundred ninety-one".