20512105551 has 70 divisors (see below), whose sum is σ = 35880697960. Its totient is φ = 11720202984.

The previous prime is 20512105541. The next prime is 20512105567. The reversal of 20512105551 is 15550121502.

20512105551 is a `hidden beast` number, since 2 + 0 + 5 + 1 + 2 + 105 + 551 = 666.

It is not a de Polignac number, because 20512105551 - 2¹⁰ = 20512104527 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20512105541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 69 ways as a sum of consecutive naturals, for example, 1744470 + ... + 1756188.

Almost surely, 2^20512105551 is an apocalyptic number.

20512105551 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20512105551 is a deficient number, since it is larger than the sum of its proper divisors (15368592409).

20512105551 is an frugal number, since it uses more digits than its factorization.

20512105551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11765 (or 11729 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

The spelling of 20512105551 in words is "twenty billion, five hundred twelve million, one hundred five thousand, five hundred fifty-one".