20736661 has 4 divisors (see below), whose sum is σ = 22621824. Its totient is φ = 18851500.

The previous prime is 20736659. The next prime is 20736673. The reversal of 20736661 is 16663702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20736661 - 2¹ = 20736659 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20736691) 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 3 ways as a sum of consecutive naturals, for example, 942565 + ... + 942586.

It is an arithmetic number, because the mean of its divisors is an integer number (5655456).

Almost surely, 2^20736661 is an apocalyptic number.

20736661 is the 2037-th centered decagonal number.

It is an amenable number.

20736661 is a deficient number, since it is larger than the sum of its proper divisors (1885163).

20736661 is a wasteful number, since it uses less digits than its factorization.

20736661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1885162.

The product of its (nonzero) digits is 9072, while the sum is 31.

The square root of 20736661 is about 4553.7524087284. The cubic root of 20736661 is about 274.7343373798.

The spelling of 20736661 in words is "twenty million, seven hundred thirty-six thousand, six hundred sixty-one".