1638969909 has 16 divisors (see below), whose sum is σ = 2245266240. Its totient is φ = 1063042560.

The previous prime is 1638969869. The next prime is 1638969911. The reversal of 1638969909 is 9099698361.

It is not a de Polignac number, because 1638969909 - 2⁷ = 1638969781 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638969919) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30562 + ... + 64899.

It is an arithmetic number, because the mean of its divisors is an integer number (140329140).

Almost surely, 2^1638969909 is an apocalyptic number.

It is an amenable number.

1638969909 is a deficient number, since it is larger than the sum of its proper divisors (606296331).

1638969909 is an equidigital number, since it uses as much as digits as its factorization.

1638969909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95620.

The product of its (nonzero) digits is 5668704, while the sum is 60.

The square root of 1638969909 is about 40484.1933228266. The cubic root of 1638969909 is about 1179.0267539994.

The spelling of 1638969909 in words is "one billion, six hundred thirty-eight million, nine hundred sixty-nine thousand, nine hundred nine".