20509851606 has 32 divisors (see below), whose sum is σ = 43207914240. Its totient is φ = 6472403424.

The previous prime is 20509851601. The next prime is 20509851611. The reversal of 20509851606 is 60615890502.

It is an interprime number because it is at equal distance from previous prime (20509851601) and next prime (20509851611).

It is a super-4 number, since 4×20509851606⁴ (a number of 42 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20509851601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109951 + ... + 230453.

It is an arithmetic number, because the mean of its divisors is an integer number (1350247320).

Almost surely, 2^20509851606 is an apocalyptic number.

20509851606 is an abundant number, since it is smaller than the sum of its proper divisors (22698062634).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20509851606 is a wasteful number, since it uses less digits than its factorization.

20509851606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122020.

The product of its (nonzero) digits is 129600, while the sum is 42.

The spelling of 20509851606 in words is "twenty billion, five hundred nine million, eight hundred fifty-one thousand, six hundred six".