20563615 has 4 divisors (see below), whose sum is σ = 24676344. Its totient is φ = 16450888.

The previous prime is 20563607. The next prime is 20563637. The reversal of 20563615 is 51636502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51636502 = 2 ⋅25818251.

It is a cyclic number.

It is not a de Polignac number, because 20563615 - 2³ = 20563607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2056357 + ... + 2056366.

It is an arithmetic number, because the mean of its divisors is an integer number (6169086).

Almost surely, 2^20563615 is an apocalyptic number.

20563615 is a deficient number, since it is larger than the sum of its proper divisors (4112729).

20563615 is an equidigital number, since it uses as much as digits as its factorization.

20563615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4112728.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 20563615 is about 4534.7122290174. The cubic root of 20563615 is about 273.9679886946.

It can be divided in two parts, 2056 and 3615, that multiplied together give a triangular number (7432440 = T₃₈₅₅).

The spelling of 20563615 in words is "twenty million, five hundred sixty-three thousand, six hundred fifteen".