20400659 has 4 divisors (see below), whose sum is σ = 21104160. Its totient is φ = 19697160.

The previous prime is 20400637. The next prime is 20400671. The reversal of 20400659 is 95600402.

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 20400659 - 2¹⁶ = 20335123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20400689) 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, 351707 + ... + 351764.

It is an arithmetic number, because the mean of its divisors is an integer number (5276040).

Almost surely, 2^20400659 is an apocalyptic number.

20400659 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20400659 is a deficient number, since it is larger than the sum of its proper divisors (703501).

20400659 is an equidigital number, since it uses as much as digits as its factorization.

20400659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 703500.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 20400659 is about 4516.7088681915. The cubic root of 20400659 is about 273.2423838129.

The spelling of 20400659 in words is "twenty million, four hundred thousand, six hundred fifty-nine".