1621166655 has 32 divisors (see below), whose sum is σ = 2690440128. Its totient is φ = 832896000.

The previous prime is 1621166647. The next prime is 1621166711. The reversal of 1621166655 is 5566611261.

It is not a de Polignac number, because 1621166655 - 2³ = 1621166647 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41595 + ... + 70515.

It is an arithmetic number, because the mean of its divisors is an integer number (84076254).

Almost surely, 2^1621166655 is an apocalyptic number.

1621166655 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1621166655 is a deficient number, since it is larger than the sum of its proper divisors (1069273473).

1621166655 is a wasteful number, since it uses less digits than its factorization.

1621166655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29067.

The product of its digits is 64800, while the sum is 39.

The square root of 1621166655 is about 40263.7138749023. The cubic root of 1621166655 is about 1174.7421567923.

The spelling of 1621166655 in words is "one billion, six hundred twenty-one million, one hundred sixty-six thousand, six hundred fifty-five".