1643604457 has 4 divisors (see below), whose sum is σ = 1793023056. Its totient is φ = 1494185860.

The previous prime is 1643604439. The next prime is 1643604467. The reversal of 1643604457 is 7544063461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7544063461 = 11 ⋅685823951.

It is a cyclic number.

It is not a de Polignac number, because 1643604457 - 2¹¹ = 1643602409 is a prime.

It is a super-2 number, since 2×1643604457² = 5402871222140529698, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1643604427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74709283 + ... + 74709304.

It is an arithmetic number, because the mean of its divisors is an integer number (448255764).

Almost surely, 2^1643604457 is an apocalyptic number.

It is an amenable number.

1643604457 is a deficient number, since it is larger than the sum of its proper divisors (149418599).

1643604457 is a wasteful number, since it uses less digits than its factorization.

1643604457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149418598.

The product of its (nonzero) digits is 241920, while the sum is 40.

The square root of 1643604457 is about 40541.3918976643. The cubic root of 1643604457 is about 1180.1370273218.

The spelling of 1643604457 in words is "one billion, six hundred forty-three million, six hundred four thousand, four hundred fifty-seven".