20399057691 has 8 divisors (see below), whose sum is σ = 27302161920. Its totient is φ = 13547662632.

The previous prime is 20399057681. The next prime is 20399057699. The reversal of 20399057691 is 19675099302.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20399057691 - 2¹⁵ = 20399024923 is a prime.

It is a super-2 number, since 2×20399057691² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (20399057699) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12926371 + ... + 12927948.

It is an arithmetic number, because the mean of its divisors is an integer number (3412770240).

Almost surely, 2^20399057691 is an apocalyptic number.

20399057691 is a deficient number, since it is larger than the sum of its proper divisors (6903104229).

20399057691 is a wasteful number, since it uses less digits than its factorization.

20399057691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25854585.

The product of its (nonzero) digits is 918540, while the sum is 51.

The spelling of 20399057691 in words is "twenty billion, three hundred ninety-nine million, fifty-seven thousand, six hundred ninety-one".