20245639 has 4 divisors (see below), whose sum is σ = 20265256. Its totient is φ = 20226024.

The previous prime is 20245637. The next prime is 20245649. The reversal of 20245639 is 93654202.

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

It is a cyclic number.

It is not a de Polignac number, because 20245639 - 2¹ = 20245637 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20245639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20245637) 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, 8169 + ... + 10354.

It is an arithmetic number, because the mean of its divisors is an integer number (5066314).

Almost surely, 2^20245639 is an apocalyptic number.

20245639 is a deficient number, since it is larger than the sum of its proper divisors (19617).

20245639 is a wasteful number, since it uses less digits than its factorization.

20245639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19616.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 20245639 is about 4499.5154183534. The cubic root of 20245639 is about 272.5485209450.

The spelling of 20245639 in words is "twenty million, two hundred forty-five thousand, six hundred thirty-nine".