20115661 has 8 divisors (see below), whose sum is σ = 21465920. Its totient is φ = 18794592.

The previous prime is 20115659. The next prime is 20115713. The reversal of 20115661 is 16651102.

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 20115661 - 2¹ = 20115659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20115061) 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, 5865 + ... + 8638.

It is an arithmetic number, because the mean of its divisors is an integer number (2683240).

Almost surely, 2^20115661 is an apocalyptic number.

It is an amenable number.

20115661 is a deficient number, since it is larger than the sum of its proper divisors (1350259).

20115661 is a wasteful number, since it uses less digits than its factorization.

20115661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14595.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20115661 is about 4485.0486062026. The cubic root of 20115661 is about 271.9640099801.

Adding to 20115661 its reverse (16651102), we get a palindrome (36766763).

The spelling of 20115661 in words is "twenty million, one hundred fifteen thousand, six hundred sixty-one".