551721618 has 40 divisors (see below), whose sum is σ = 1412877312. Its totient is φ = 157634424.

The previous prime is 551721613. The next prime is 551721629. The reversal of 551721618 is 816127155.

551721618 is a `hidden beast` number, since 5 + 5 + 17 + 21 + 618 = 666.

It is not an unprimeable number, because it can be changed into a prime (551721613) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 242130 + ... + 244397.

Almost surely, 2^551721618 is an apocalyptic number.

551721618 is an abundant number, since it is smaller than the sum of its proper divisors (861155694).

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

551721618 is a wasteful number, since it uses less digits than its factorization.

551721618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486548 (or 486539 counting only the distinct ones).

The product of its digits is 16800, while the sum is 36.

The square root of 551721618 is about 23488.7551394279. The cubic root of 551721618 is about 820.1752639449.

The spelling of 551721618 in words is "five hundred fifty-one million, seven hundred twenty-one thousand, six hundred eighteen".