20505211218438 has 16 divisors (see below), whose sum is σ = 41882984616960. Its totient is φ = 6689643376136.

The previous prime is 20505211218409. The next prime is 20505211218467. The reversal of 20505211218438 is 83481211250502.

It is an interprime number because it is at equal distance from previous prime (20505211218409) and next prime (20505211218467).

It is a super-2 number, since 2×20505211218438² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20505211218438.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36356757198 + ... + 36356757761.

It is an arithmetic number, because the mean of its divisors is an integer number (2617686538560).

Almost surely, 2^{20505211218438} is an apocalyptic number.

20505211218438 is an abundant number, since it is smaller than the sum of its proper divisors (21377773398522).

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

20505211218438 is a wasteful number, since it uses less digits than its factorization.

20505211218438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72713515011.

The product of its (nonzero) digits is 153600, while the sum is 42.

The spelling of 20505211218438 in words is "twenty trillion, five hundred five billion, two hundred eleven million, two hundred eighteen thousand, four hundred thirty-eight".