21956126977 has 4 divisors (see below), whose sum is σ = 23247663876. Its totient is φ = 20664590080.

The previous prime is 21956126963. The next prime is 21956126981. The reversal of 21956126977 is 77962165912.

It is a happy number.

It is a Cunningham number, because it is equal to 148176²+1.

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 17093993536 + 4862133441 = 130744^2 + 69729^2 .

It is a cyclic number.

It is not a de Polignac number, because 21956126977 - 2²³ = 21947738369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21956126917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 645768424 + ... + 645768457.

It is an arithmetic number, because the mean of its divisors is an integer number (5811915969).

Almost surely, 2^21956126977 is an apocalyptic number.

It is an amenable number.

21956126977 is a deficient number, since it is larger than the sum of its proper divisors (1291536899).

21956126977 is a wasteful number, since it uses less digits than its factorization.

21956126977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1291536898.

The product of its digits is 2857680, while the sum is 55.

The spelling of 21956126977 in words is "twenty-one billion, nine hundred fifty-six million, one hundred twenty-six thousand, nine hundred seventy-seven".