1551555661666 has 32 divisors (see below), whose sum is σ = 2480928134400. Its totient is φ = 725201607936.

The previous prime is 1551555661631. The next prime is 1551555661679. The reversal of 1551555661666 is 6661665551551.

It is a self number, because there is not a number n which added to its sum of digits gives 1551555661666.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13517385 + ... + 13631683.

It is an arithmetic number, because the mean of its divisors is an integer number (77529004200).

Almost surely, 2^{1551555661666} is an apocalyptic number.

1551555661666 is a deficient number, since it is larger than the sum of its proper divisors (929372472734).

1551555661666 is a wasteful number, since it uses less digits than its factorization.

1551555661666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117018.

The product of its digits is 24300000, while the sum is 58.

The spelling of 1551555661666 in words is "one trillion, five hundred fifty-one billion, five hundred fifty-five million, six hundred sixty-one thousand, six hundred sixty-six".