1551661511655 has 32 divisors (see below), whose sum is σ = 2590688987136. Its totient is φ = 791545086464.

The previous prime is 1551661511597. The next prime is 1551661511671. The reversal of 1551661511655 is 5561151661551.

It is a cyclic number.

It is not a de Polignac number, because 1551661511655 - 2¹⁷ = 1551661380583 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13394914 + ... + 13510256.

It is an arithmetic number, because the mean of its divisors is an integer number (80959030848).

Almost surely, 2^{1551661511655} is an apocalyptic number.

1551661511655 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1551661511655 is a deficient number, since it is larger than the sum of its proper divisors (1039027475481).

1551661511655 is a wasteful number, since it uses less digits than its factorization.

1551661511655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154367.

The product of its digits is 675000, while the sum is 48.

The spelling of 1551661511655 in words is "one trillion, five hundred fifty-one billion, six hundred sixty-one million, five hundred eleven thousand, six hundred fifty-five".