1645021601943 has 4 divisors (see below), whose sum is σ = 2193362135928. Its totient is φ = 1096681067960.

The previous prime is 1645021601933. The next prime is 1645021601957. The reversal of 1645021601943 is 3491061205461.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1645021601943 - 2¹⁶ = 1645021536407 is a prime.

It is a super-2 number, since 2×1645021601943² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1645021601895 and 1645021601904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645021601933) 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, 274170266988 + ... + 274170266993.

It is an arithmetic number, because the mean of its divisors is an integer number (548340533982).

Almost surely, 2^{1645021601943} is an apocalyptic number.

1645021601943 is a deficient number, since it is larger than the sum of its proper divisors (548340533985).

1645021601943 is an equidigital number, since it uses as much as digits as its factorization.

1645021601943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548340533984.

The product of its (nonzero) digits is 155520, while the sum is 42.

The spelling of 1645021601943 in words is "one trillion, six hundred forty-five billion, twenty-one million, six hundred one thousand, nine hundred forty-three".