551646801981 has 12 divisors (see below), whose sum is σ = 869261627520. Its totient is φ = 334331395080.

The previous prime is 551646801973. The next prime is 551646801991. The reversal of 551646801981 is 189108646155.

551646801981 is a `hidden beast` number, since 5 + 516 + 46 + 8 + 0 + 1 + 9 + 81 = 666.

It is not a de Polignac number, because 551646801981 - 2³ = 551646801973 is a prime.

It is a super-2 number, since 2×551646801981² (a number of 24 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (551646801931) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2786094861 + ... + 2786095058.

It is an arithmetic number, because the mean of its divisors is an integer number (72438468960).

Almost surely, 2^551646801981 is an apocalyptic number.

It is an amenable number.

551646801981 is a deficient number, since it is larger than the sum of its proper divisors (317614825539).

551646801981 is a wasteful number, since it uses less digits than its factorization.

551646801981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5572189936 (or 5572189933 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 54.

The spelling of 551646801981 in words is "five hundred fifty-one billion, six hundred forty-six million, eight hundred one thousand, nine hundred eighty-one".