20461681 has 4 divisors (see below), whose sum is σ = 20742052. Its totient is φ = 20181312.

The previous prime is 20461673. The next prime is 20461699. The reversal of 20461681 is 18616402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8071281 + 12390400 = 2841^2 + 3520^2 .

It is a cyclic number.

It is not a de Polignac number, because 20461681 - 2³ = 20461673 is a prime.

It is a super-2 number, since 2×20461681² = 837360778691522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20461631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 140076 + ... + 140221.

It is an arithmetic number, because the mean of its divisors is an integer number (5185513).

Almost surely, 2^20461681 is an apocalyptic number.

It is an amenable number.

20461681 is a deficient number, since it is larger than the sum of its proper divisors (280371).

20461681 is an equidigital number, since it uses as much as digits as its factorization.

20461681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280370.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 20461681 is about 4523.4589641114. The cubic root of 20461681 is about 273.5145514841.

The spelling of 20461681 in words is "twenty million, four hundred sixty-one thousand, six hundred eighty-one".