19776515641 has 3 divisors (see below), whose sum is σ = 19776656271. Its totient is φ = 19776375012.

The previous prime is 19776515623. The next prime is 19776515653. The reversal of 19776515641 is 14651567791.

It is a happy number.

The square root of 19776515641 is 140629.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 14651567791 = 7 ⋅2093081113.

It can be written as a sum of positive squares in only one way, i.e., 19774265641 + 2250000 = 140621^2 + 1500^2 .

It is not a de Polignac number, because 19776515641 - 2⁷ = 19776515513 is a prime.

It is a super-2 number, since 2×19776515641² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19776515741) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 70315 + ... + 210943.

It is an arithmetic number, because the mean of its divisors is an integer number (6592218757).

Almost surely, 2^19776515641 is an apocalyptic number.

19776515641 is the 140629-th square number.

19776515641 is the 70315-th centered octagonal number.

It is an amenable number.

19776515641 is a deficient number, since it is larger than the sum of its proper divisors (140630).

19776515641 is an frugal number, since it uses more digits than its factorization.

19776515641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281258 (or 140629 counting only the distinct ones).

The product of its digits is 1587600, while the sum is 52.

The spelling of 19776515641 in words is "nineteen billion, seven hundred seventy-six million, five hundred fifteen thousand, six hundred forty-one".