1638700729 has 2 divisors, whose sum is σ = 1638700730. Its totient is φ = 1638700728.

The previous prime is 1638700681. The next prime is 1638700741. The reversal of 1638700729 is 9270078361.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1265438329 + 373262400 = 35573^2 + 19320^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638700729 is a prime.

It is not a weakly prime, because it can be changed into another prime (1638700759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819350364 + 819350365.

It is an arithmetic number, because the mean of its divisors is an integer number (819350365).

Almost surely, 2^1638700729 is an apocalyptic number.

It is an amenable number.

1638700729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638700729 is an equidigital number, since it uses as much as digits as its factorization.

1638700729 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 43.

The square root of 1638700729 is about 40480.8686789204. The cubic root of 1638700729 is about 1178.9622037401.

The spelling of 1638700729 in words is "one billion, six hundred thirty-eight million, seven hundred thousand, seven hundred twenty-nine".