21011220977 has 2 divisors, whose sum is σ = 21011220978. Its totient is φ = 21011220976.

The previous prime is 21011220961. The next prime is 21011220983. The reversal of 21011220977 is 77902211012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19455786256 + 1555434721 = 139484^2 + 39439^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011220977 - 2⁴ = 21011220961 is a prime.

It is a super-3 number, since 3×21011220977³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21011220917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505610488 + 10505610489.

It is an arithmetic number, because the mean of its divisors is an integer number (10505610489).

Almost surely, 2^21011220977 is an apocalyptic number.

It is an amenable number.

21011220977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011220977 is an equidigital number, since it uses as much as digits as its factorization.

21011220977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3528, while the sum is 32.

Adding to 21011220977 its reverse (77902211012), we get a palindrome (98913431989).

The spelling of 21011220977 in words is "twenty-one billion, eleven million, two hundred twenty thousand, nine hundred seventy-seven".