20578502509 has 4 divisors (see below), whose sum is σ = 20767296220. Its totient is φ = 20389708800.

The previous prime is 20578502489. The next prime is 20578502537. The reversal of 20578502509 is 90520587502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90520587502 = 2 ⋅45260293751.

It can be written as a sum of positive squares in 2 ways, for example, as 13607922409 + 6970580100 = 116653^2 + 83490^2 .

It is a cyclic number.

It is not a de Polignac number, because 20578502509 - 2⁷ = 20578502381 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 (20578502599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94396692 + ... + 94396909.

It is an arithmetic number, because the mean of its divisors is an integer number (5191824055).

Almost surely, 2^20578502509 is an apocalyptic number.

It is an amenable number.

20578502509 is a deficient number, since it is larger than the sum of its proper divisors (188793711).

20578502509 is a wasteful number, since it uses less digits than its factorization.

20578502509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188793710.

The product of its (nonzero) digits is 252000, while the sum is 43.

The spelling of 20578502509 in words is "twenty billion, five hundred seventy-eight million, five hundred two thousand, five hundred nine".