20661081 has 8 divisors (see below), whose sum is σ = 31483584. Its totient is φ = 11806320.

The previous prime is 20661049. The next prime is 20661101. The reversal of 20661081 is 18016602.

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

It is not a de Polignac number, because 20661081 - 2⁵ = 20661049 is a prime.

It is a super-2 number, since 2×20661081² = 853760536177122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20661041) by changing a digit.

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, 491910 + ... + 491951.

It is an arithmetic number, because the mean of its divisors is an integer number (3935448).

Almost surely, 2^20661081 is an apocalyptic number.

20661081 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20661081 is a deficient number, since it is larger than the sum of its proper divisors (10822503).

20661081 is an equidigital number, since it uses as much as digits as its factorization.

20661081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983871.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 20661081 is about 4545.4461827196. The cubic root of 20661081 is about 274.4001514745.

Adding to 20661081 its reverse (18016602), we get a palindrome (38677683).

The spelling of 20661081 in words is "twenty million, six hundred sixty-one thousand, eighty-one".