19551651981 has 8 divisors (see below), whose sum is σ = 26909800704. Its totient is φ = 12613968960.

The previous prime is 19551651979. The next prime is 19551652007. The reversal of 19551651981 is 18915615591.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19551651981 - 2¹ = 19551651979 is a prime.

It is a super-3 number, since 3×19551651981³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19551651901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105116316 + ... + 105116501.

It is an arithmetic number, because the mean of its divisors is an integer number (3363725088).

Almost surely, 2^19551651981 is an apocalyptic number.

It is an amenable number.

19551651981 is a deficient number, since it is larger than the sum of its proper divisors (7358148723).

19551651981 is a wasteful number, since it uses less digits than its factorization.

19551651981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210232851.

The product of its digits is 486000, while the sum is 51.

The spelling of 19551651981 in words is "nineteen billion, five hundred fifty-one million, six hundred fifty-one thousand, nine hundred eighty-one".