19402540638 has 32 divisors (see below), whose sum is σ = 42002253216. Its totient is φ = 5939703168.

The previous prime is 19402540603. The next prime is 19402540649. The reversal of 19402540638 is 83604520491.

It is a self number, because there is not a number n which added to its sum of digits gives 19402540638.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 615981 + ... + 646712.

It is an arithmetic number, because the mean of its divisors is an integer number (1312570413).

Almost surely, 2^19402540638 is an apocalyptic number.

19402540638 is an abundant number, since it is smaller than the sum of its proper divisors (22599712578).

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

19402540638 is a wasteful number, since it uses less digits than its factorization.

19402540638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262908.

The product of its (nonzero) digits is 207360, while the sum is 42.

The spelling of 19402540638 in words is "nineteen billion, four hundred two million, five hundred forty thousand, six hundred thirty-eight".