19640503861 has 4 divisors (see below), whose sum is σ = 21426004224. Its totient is φ = 17855003500.

The previous prime is 19640503847. The next prime is 19640503931. The reversal of 19640503861 is 16830504691.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19640503861 - 2⁹ = 19640503349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19640503811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 892750165 + ... + 892750186.

It is an arithmetic number, because the mean of its divisors is an integer number (5356501056).

Almost surely, 2^19640503861 is an apocalyptic number.

19640503861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19640503861 is a deficient number, since it is larger than the sum of its proper divisors (1785500363).

19640503861 is a wasteful number, since it uses less digits than its factorization.

19640503861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1785500362.

The product of its (nonzero) digits is 155520, while the sum is 43.

The spelling of 19640503861 in words is "nineteen billion, six hundred forty million, five hundred three thousand, eight hundred sixty-one".