1641688639 has 4 divisors (see below), whose sum is σ = 1641779440. Its totient is φ = 1641597840.

The previous prime is 1641688619. The next prime is 1641688649. The reversal of 1641688639 is 9368861461.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9368861461 = 22549 ⋅415489.

It is a cyclic number.

It is not a de Polignac number, because 1641688639 - 2⁹ = 1641688127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641688619) 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, 8022 + ... + 57859.

It is an arithmetic number, because the mean of its divisors is an integer number (410444860).

Almost surely, 2^1641688639 is an apocalyptic number.

1641688639 is a deficient number, since it is larger than the sum of its proper divisors (90801).

1641688639 is an equidigital number, since it uses as much as digits as its factorization.

1641688639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90800.

The product of its digits is 1492992, while the sum is 52.

The square root of 1641688639 is about 40517.7570825435. The cubic root of 1641688639 is about 1179.6783186628.

The spelling of 1641688639 in words is "one billion, six hundred forty-one million, six hundred eighty-eight thousand, six hundred thirty-nine".