1641645 has 18 divisors (see below), whose sum is σ = 2860494. Its totient is φ = 870960.

The previous prime is 1641641. The next prime is 1641659. The reversal of 1641645 is 5461461.

1641645 is a `hidden beast` number, since 16 + 4 + 1 + 645 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1313316 + 328329 = 1146^2 + 573^2 .

It is not a de Polignac number, because 1641645 - 2² = 1641641 is a prime.

It is a super-3 number, since 3×1641645³ = 13272691482283233375, which contains 333 as substring.

1641645 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641641) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 8500 + ... + 8690.

2^1641645 is an apocalyptic number.

1641645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1641645 is a deficient number, since it is larger than the sum of its proper divisors (1218849).

1641645 is an equidigital number, since it uses as much as digits as its factorization.

1641645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393 (or 199 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 1641645 is about 1281.2669511074. The cubic root of 1641645 is about 117.9667865922.

Multiplying 1641645 by its product of digits (2880), we get a square (4727937600 = 68760²).

It can be divided in two parts, 16416 and 45, that multiplied together give a triangular number (738720 = T₁₂₁₅).

The spelling of 1641645 in words is "one million, six hundred forty-one thousand, six hundred forty-five".