20617649 has 4 divisors (see below), whose sum is σ = 22203636. Its totient is φ = 19031664.

The previous prime is 20617643. The next prime is 20617669. The reversal of 20617649 is 94671602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5094049 + 15523600 = 2257^2 + 3940^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20617649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20617643) 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, 792974 + ... + 792999.

It is an arithmetic number, because the mean of its divisors is an integer number (5550909).

Almost surely, 2^20617649 is an apocalyptic number.

It is an amenable number.

20617649 is a deficient number, since it is larger than the sum of its proper divisors (1585987).

20617649 is a wasteful number, since it uses less digits than its factorization.

20617649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1585986.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 20617649 is about 4540.6661405569. Note that the first 3 decimals coincide. The cubic root of 20617649 is about 274.2077428912.

The spelling of 20617649 in words is "twenty million, six hundred seventeen thousand, six hundred forty-nine".