20355691 has 4 divisors (see below), whose sum is σ = 20365984. Its totient is φ = 20345400.

The previous prime is 20355689. The next prime is 20355703. The reversal of 20355691 is 19655302.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20355691 - 2¹ = 20355689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20355191) 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, 1140 + ... + 6481.

It is an arithmetic number, because the mean of its divisors is an integer number (5091496).

Almost surely, 2^20355691 is an apocalyptic number.

20355691 is a deficient number, since it is larger than the sum of its proper divisors (10293).

20355691 is an equidigital number, since it uses as much as digits as its factorization.

20355691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10292.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 20355691 is about 4511.7281611374. The cubic root of 20355691 is about 273.0414719609.

The spelling of 20355691 in words is "twenty million, three hundred fifty-five thousand, six hundred ninety-one".