20615641 has 4 divisors (see below), whose sum is σ = 20630500. Its totient is φ = 20600784.

The previous prime is 20615629. The next prime is 20615653. The reversal of 20615641 is 14651602.

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

It is an interprime number because it is at equal distance from previous prime (20615629) and next prime (20615653).

It can be written as a sum of positive squares in 2 ways, for example, as 2468041 + 18147600 = 1571^2 + 4260^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20615641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20615671) 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, 5106 + ... + 8203.

It is an arithmetic number, because the mean of its divisors is an integer number (5157625).

Almost surely, 2^20615641 is an apocalyptic number.

It is an amenable number.

20615641 is a deficient number, since it is larger than the sum of its proper divisors (14859).

20615641 is a wasteful number, since it uses less digits than its factorization.

20615641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14858.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 20615641 is about 4540.4450222418. The cubic root of 20615641 is about 274.1988406957.

The spelling of 20615641 in words is "twenty million, six hundred fifteen thousand, six hundred forty-one".