19988656507 has 16 divisors (see below), whose sum is σ = 21119932960. Its totient is φ = 18865446912.

The previous prime is 19988656453. The next prime is 19988656517. The reversal of 19988656507 is 70565688991.

It is a 13-Lehmer number, since φ(19988656507) divides (19988656507-1)¹³.

It is a cyclic number.

It is not a de Polignac number, because 19988656507 - 2⁷ = 19988656379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19988656517) 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, 7707403 + ... + 7709995.

It is an arithmetic number, because the mean of its divisors is an integer number (1319995810).

Almost surely, 2^19988656507 is an apocalyptic number.

19988656507 is the 81627-th hex number.

19988656507 is a deficient number, since it is larger than the sum of its proper divisors (1131276453).

19988656507 is a wasteful number, since it uses less digits than its factorization.

19988656507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3982.

The product of its (nonzero) digits is 32659200, while the sum is 64.

The spelling of 19988656507 in words is "nineteen billion, nine hundred eighty-eight million, six hundred fifty-six thousand, five hundred seven".