20502661 has 4 divisors (see below), whose sum is σ = 20533024. Its totient is φ = 20472300.

The previous prime is 20502641. The next prime is 20502667. The reversal of 20502661 is 16620502.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16620502 = 2 ⋅8310251.

It is a cyclic number.

It is not a de Polignac number, because 20502661 - 2⁷ = 20502533 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 (20502667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14145 + ... + 15526.

It is an arithmetic number, because the mean of its divisors is an integer number (5133256).

Almost surely, 2^20502661 is an apocalyptic number.

It is an amenable number.

20502661 is a deficient number, since it is larger than the sum of its proper divisors (30363).

20502661 is an equidigital number, since it uses as much as digits as its factorization.

20502661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30362.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 20502661 is about 4527.9864178242. The cubic root of 20502661 is about 273.6970251182.

It can be divided in two parts, 20 and 502661, that added together give a square (502681 = 709²).

The spelling of 20502661 in words is "twenty million, five hundred two thousand, six hundred sixty-one".