20631605 has 8 divisors (see below), whose sum is σ = 24783192. Its totient is φ = 16488448.

The previous prime is 20631601. The next prime is 20631617. The reversal of 20631605 is 50613602.

It can be written as a sum of positive squares in 4 ways, for example, as 579121 + 20052484 = 761^2 + 4478^2 .

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 20631605 - 2² = 20631601 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 (20631601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6437 + ... + 9093.

It is an arithmetic number, because the mean of its divisors is an integer number (3097899).

Almost surely, 2^20631605 is an apocalyptic number.

It is an amenable number.

20631605 is a deficient number, since it is larger than the sum of its proper divisors (4151587).

20631605 is a wasteful number, since it uses less digits than its factorization.

20631605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4215.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 20631605 is about 4542.2026595034. The cubic root of 20631605 is about 274.2695989597.

The spelling of 20631605 in words is "twenty million, six hundred thirty-one thousand, six hundred five".