1643400013 has 8 divisors (see below), whose sum is σ = 1742715000. Its totient is φ = 1544378880.

The previous prime is 1643399969. The next prime is 1643400049. The reversal of 1643400013 is 3100043461.

It can be written as a sum of positive squares in 4 ways, for example, as 1129833769 + 513566244 = 33613^2 + 22662^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1643400013 - 2⁹ = 1643399501 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 (1643400413) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61888 + ... + 84361.

It is an arithmetic number, because the mean of its divisors is an integer number (217839375).

Almost surely, 2^1643400013 is an apocalyptic number.

It is an amenable number.

1643400013 is a deficient number, since it is larger than the sum of its proper divisors (99314987).

1643400013 is a wasteful number, since it uses less digits than its factorization.

1643400013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146927.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 1643400013 is about 40538.8703962012. The cubic root of 1643400013 is about 1180.0880938253.

Adding to 1643400013 its reverse (3100043461), we get a palindrome (4743443474).

The spelling of 1643400013 in words is "one billion, six hundred forty-three million, four hundred thousand, thirteen".