20661005 has 8 divisors (see below), whose sum is σ = 25200024. Its totient is φ = 16257600.

The previous prime is 20660993. The next prime is 20661013. The reversal of 20661005 is 50016602.

It can be written as a sum of positive squares in 4 ways, for example, as 131044 + 20529961 = 362^2 + 4531^2 .

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

It is not a de Polignac number, because 20661005 - 2⁴ = 20660989 is a prime.

It is a super-2 number, since 2×20661005² = 853754255220050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33566 + ... + 34175.

It is an arithmetic number, because the mean of its divisors is an integer number (3150003).

Almost surely, 2^20661005 is an apocalyptic number.

It is an amenable number.

20661005 is a deficient number, since it is larger than the sum of its proper divisors (4539019).

20661005 is an equidigital number, since it uses as much as digits as its factorization.

20661005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67807.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 20661005 is about 4545.4378226965. The cubic root of 20661005 is about 274.3998150217.

Adding to 20661005 its reverse (50016602), we get a palindrome (70677607).

The spelling of 20661005 in words is "twenty million, six hundred sixty-one thousand, five".