21080977 has 2 divisors, whose sum is σ = 21080978. Its totient is φ = 21080976.

The previous prime is 21080963. The next prime is 21080987. The reversal of 21080977 is 77908012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13512976 + 7568001 = 3676^2 + 2751^2 .

It is a cyclic number.

It is not a de Polignac number, because 21080977 - 2⁷ = 21080849 is a prime.

It is not a weakly prime, because it can be changed into another prime (21080987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10540488 + 10540489.

It is an arithmetic number, because the mean of its divisors is an integer number (10540489).

Almost surely, 2^21080977 is an apocalyptic number.

It is an amenable number.

21080977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21080977 is an equidigital number, since it uses as much as digits as its factorization.

21080977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 21080977 is about 4591.4025090380. The cubic root of 21080977 is about 276.2465809040.

Adding to 21080977 its reverse (77908012), we get a palindrome (98988989).

The spelling of 21080977 in words is "twenty-one million, eighty thousand, nine hundred seventy-seven".