21995976787 has 6 divisors (see below), whose sum is σ = 22325507108. Its totient is φ = 21666482772.

The previous prime is 21995976773. The next prime is 21995976803. The reversal of 21995976787 is 78767959912.

It is a de Polignac number, because none of the positive numbers 2^k-21995976787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21995976707) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1204914 + ... + 1223032.

Almost surely, 2^21995976787 is an apocalyptic number.

21995976787 is a deficient number, since it is larger than the sum of its proper divisors (329530321).

21995976787 is an frugal number, since it uses more digits than its factorization.

21995976787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36305 (or 18186 counting only the distinct ones).

The product of its digits is 120022560, while the sum is 70.

The spelling of 21995976787 in words is "twenty-one billion, nine hundred ninety-five million, nine hundred seventy-six thousand, seven hundred eighty-seven".