19621046551 has 4 divisors (see below), whose sum is σ = 20099608704. Its totient is φ = 19142484400.

The previous prime is 19621046539. The next prime is 19621046567. The reversal of 19621046551 is 15564012691.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15564012691 = 20063 ⋅775757.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19621046551 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19621046581) 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, 239281015 + ... + 239281096.

It is an arithmetic number, because the mean of its divisors is an integer number (5024902176).

Almost surely, 2^19621046551 is an apocalyptic number.

19621046551 is a deficient number, since it is larger than the sum of its proper divisors (478562153).

19621046551 is an equidigital number, since it uses as much as digits as its factorization.

19621046551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478562152.

The product of its (nonzero) digits is 64800, while the sum is 40.

The spelling of 19621046551 in words is "nineteen billion, six hundred twenty-one million, forty-six thousand, five hundred fifty-one".