19780627981 has 4 divisors (see below), whose sum is σ = 20263082364. Its totient is φ = 19298173600.

The previous prime is 19780627973. The next prime is 19780627987. The reversal of 19780627981 is 18972608791.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 856498756 + 18924129225 = 29266^2 + 137565^2 .

It is a cyclic number.

It is not a de Polignac number, because 19780627981 - 2³ = 19780627973 is a prime.

It is a super-2 number, since 2×19780627981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19780627987) 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, 241227130 + ... + 241227211.

It is an arithmetic number, because the mean of its divisors is an integer number (5065770591).

Almost surely, 2^19780627981 is an apocalyptic number.

It is an amenable number.

19780627981 is a deficient number, since it is larger than the sum of its proper divisors (482454383).

19780627981 is an equidigital number, since it uses as much as digits as its factorization.

19780627981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482454382.

The product of its (nonzero) digits is 3048192, while the sum is 58.

The spelling of 19780627981 in words is "nineteen billion, seven hundred eighty million, six hundred twenty-seven thousand, nine hundred eighty-one".