19518373640 has 16 divisors (see below), whose sum is σ = 43916340780. Its totient is φ = 7807349440.

The previous prime is 19518373639. The next prime is 19518373691. The reversal of 19518373640 is 4637381591.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19270437124 + 247936516 = 138818^2 + 15746^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 243979631 + ... + 243979710.

Almost surely, 2^19518373640 is an apocalyptic number.

19518373640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19518373640 is an abundant number, since it is smaller than the sum of its proper divisors (24397967140).

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

19518373640 is a wasteful number, since it uses less digits than its factorization.

19518373640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 487959352 (or 487959348 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 47.

The spelling of 19518373640 in words is "nineteen billion, five hundred eighteen million, three hundred seventy-three thousand, six hundred forty".