19720661853 has 4 divisors (see below), whose sum is σ = 26294215808. Its totient is φ = 13147107900.

The previous prime is 19720661833. The next prime is 19720661893. The reversal of 19720661853 is 35816602791.

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 not a de Polignac number, because 19720661853 - 2⁶ = 19720661789 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 (19720661813) 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, 3286776973 + ... + 3286776978.

It is an arithmetic number, because the mean of its divisors is an integer number (6573553952).

Almost surely, 2^19720661853 is an apocalyptic number.

It is an amenable number.

19720661853 is a deficient number, since it is larger than the sum of its proper divisors (6573553955).

19720661853 is an equidigital number, since it uses as much as digits as its factorization.

19720661853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6573553954.

The product of its (nonzero) digits is 544320, while the sum is 48.

The spelling of 19720661853 in words is "nineteen billion, seven hundred twenty million, six hundred sixty-one thousand, eight hundred fifty-three".