20401985 has 8 divisors (see below), whose sum is σ = 25144296. Its totient is φ = 15880320.

The previous prime is 20401973. The next prime is 20402009. The reversal of 20401985 is 58910402.

It can be written as a sum of positive squares in 4 ways, for example, as 3690241 + 16711744 = 1921^2 + 4088^2 .

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

It is not a de Polignac number, because 20401985 - 2⁸ = 20401729 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54956 + ... + 55325.

It is an arithmetic number, because the mean of its divisors is an integer number (3143037).

Almost surely, 2^20401985 is an apocalyptic number.

It is an amenable number.

20401985 is a deficient number, since it is larger than the sum of its proper divisors (4742311).

20401985 is a wasteful number, since it uses less digits than its factorization.

20401985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110323.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20401985 is about 4516.8556541028. The cubic root of 20401985 is about 273.2483037451.

The spelling of 20401985 in words is "twenty million, four hundred one thousand, nine hundred eighty-five".