20402689 has 8 divisors (see below), whose sum is σ = 21326760. Its totient is φ = 19493376.

The previous prime is 20402687. The next prime is 20402693. The reversal of 20402689 is 98620402.

It can be written as a sum of positive squares in 4 ways, for example, as 4665600 + 15737089 = 2160^2 + 3967^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20402689 - 2¹ = 20402687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20402689.

It is not an unprimeable number, because it can be changed into a prime (20402687) 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, 814 + ... + 6439.

It is an arithmetic number, because the mean of its divisors is an integer number (2665845).

Almost surely, 2^20402689 is an apocalyptic number.

20402689 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

20402689 is a deficient number, since it is larger than the sum of its proper divisors (924071).

20402689 is an equidigital number, since it uses as much as digits as its factorization.

20402689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7379.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 20402689 is about 4516.9335837490. The cubic root of 20402689 is about 273.2514466516.

The spelling of 20402689 in words is "twenty million, four hundred two thousand, six hundred eighty-nine".