21778497819 has 36 divisors (see below), whose sum is σ = 36067600296. Its totient is φ = 12613775616.

The previous prime is 21778497803. The next prime is 21778497821. The reversal of 21778497819 is 91879487712.

It is not a de Polignac number, because 21778497819 - 2⁴ = 21778497803 is a prime.

It is a super-2 number, since 2×21778497819² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21778490819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 395277 + ... + 446990.

It is an arithmetic number, because the mean of its divisors is an integer number (1001877786).

Almost surely, 2^21778497819 is an apocalyptic number.

21778497819 is a deficient number, since it is larger than the sum of its proper divisors (14289102477).

21778497819 is a wasteful number, since it uses less digits than its factorization.

21778497819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 842316 (or 842300 counting only the distinct ones).

The product of its digits is 14224896, while the sum is 63.

The spelling of 21778497819 in words is "twenty-one billion, seven hundred seventy-eight million, four hundred ninety-seven thousand, eight hundred nineteen".