21946599778 has 4 divisors (see below), whose sum is σ = 32919899670. Its totient is φ = 10973299888.

The previous prime is 21946599749. The next prime is 21946599827. The reversal of 21946599778 is 87799564912.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 21718801129 + 227798649 = 147373^2 + 15093^2 .

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5486649943 + ... + 5486649946.

Almost surely, 2^21946599778 is an apocalyptic number.

21946599778 is a deficient number, since it is larger than the sum of its proper divisors (10973299892).

21946599778 is a wasteful number, since it uses less digits than its factorization.

21946599778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10973299891.

The product of its digits is 68584320, while the sum is 67.

The spelling of 21946599778 in words is "twenty-one billion, nine hundred forty-six million, five hundred ninety-nine thousand, seven hundred seventy-eight".