1643642155 has 4 divisors (see below), whose sum is σ = 1972370592. Its totient is φ = 1314913720.

The previous prime is 1643642113. The next prime is 1643642159. The reversal of 1643642155 is 5512463461.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1643642155 - 2¹¹ = 1643640107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1643642159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164364211 + ... + 164364220.

It is an arithmetic number, because the mean of its divisors is an integer number (493092648).

Almost surely, 2^1643642155 is an apocalyptic number.

1643642155 is a deficient number, since it is larger than the sum of its proper divisors (328728437).

1643642155 is an equidigital number, since it uses as much as digits as its factorization.

1643642155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328728436.

The product of its digits is 86400, while the sum is 37.

The square root of 1643642155 is about 40541.8568272347. The cubic root of 1643642155 is about 1180.1460498628.

The spelling of 1643642155 in words is "one billion, six hundred forty-three million, six hundred forty-two thousand, one hundred fifty-five".