1643120655 has 32 divisors (see below), whose sum is σ = 2884066560. Its totient is φ = 792199680.

The previous prime is 1643120653. The next prime is 1643120693. The reversal of 1643120655 is 5560213461.

It is not a de Polignac number, because 1643120655 - 2¹ = 1643120653 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643120653) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1719 + ... + 57351.

It is an arithmetic number, because the mean of its divisors is an integer number (90127080).

Almost surely, 2^1643120655 is an apocalyptic number.

1643120655 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1643120655 is a deficient number, since it is larger than the sum of its proper divisors (1240945905).

1643120655 is a wasteful number, since it uses less digits than its factorization.

1643120655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55831.

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 1643120655 is about 40535.4246924835. The cubic root of 1643120655 is about 1180.0212231652.

The spelling of 1643120655 in words is "one billion, six hundred forty-three million, one hundred twenty thousand, six hundred fifty-five".