20315661 has 12 divisors (see below), whose sum is σ = 27445728. Its totient is φ = 13366984.

The previous prime is 20315657. The next prime is 20315671. The reversal of 20315661 is 16651302.

It is not a de Polignac number, because 20315661 - 2² = 20315657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20315671) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20176 + ... + 21158.

It is an arithmetic number, because the mean of its divisors is an integer number (2287144).

Almost surely, 2^20315661 is an apocalyptic number.

It is an amenable number.

20315661 is a deficient number, since it is larger than the sum of its proper divisors (7130067).

20315661 is an frugal number, since it uses more digits than its factorization.

20315661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1152 (or 1069 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 20315661 is about 4507.2897621520. The cubic root of 20315661 is about 272.8623734379.

Adding to 20315661 its reverse (16651302), we get a palindrome (36966963).

The spelling of 20315661 in words is "twenty million, three hundred fifteen thousand, six hundred sixty-one".