9945988638 has 16 divisors (see below), whose sum is σ = 19901932416. Its totient is φ = 3313670360.

The previous prime is 9945988631. The next prime is 9945988643. The reversal of 9945988638 is 8368895499.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9945988631) 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, 401778 + ... + 425813.

It is an arithmetic number, because the mean of its divisors is an integer number (1243870776).

Almost surely, 2^9945988638 is an apocalyptic number.

9945988638 is an abundant number, since it is smaller than the sum of its proper divisors (9955943778).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9945988638 is a wasteful number, since it uses less digits than its factorization.

9945988638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 829599.

The product of its digits is 134369280, while the sum is 69.

The square root of 9945988638 is about 99729.5775484886. The cubic root of 9945988638 is about 2150.5488872974.

It can be divided in two parts, 994598 and 8638, that added together give a triangular number (1003236 = T₁₄₁₆).

The spelling of 9945988638 in words is "nine billion, nine hundred forty-five million, nine hundred eighty-eight thousand, six hundred thirty-eight".