20691993 has 32 divisors (see below), whose sum is σ = 33212160. Its totient is φ = 11208960.

The previous prime is 20691989. The next prime is 20692013. The reversal of 20691993 is 39919602.

It is a happy number.

It is not a de Polignac number, because 20691993 - 2² = 20691989 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20690993) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36871 + ... + 37427.

It is an arithmetic number, because the mean of its divisors is an integer number (1037880).

Almost surely, 2^20691993 is an apocalyptic number.

It is an amenable number.

20691993 is a deficient number, since it is larger than the sum of its proper divisors (12520167).

20691993 is a wasteful number, since it uses less digits than its factorization.

20691993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 20691993 is about 4548.8452380797. The cubic root of 20691993 is about 274.5369308741.

The spelling of 20691993 in words is "twenty million, six hundred ninety-one thousand, nine hundred ninety-three".