21145306577 has 2 divisors, whose sum is σ = 21145306578. Its totient is φ = 21145306576.

The previous prime is 21145306447. The next prime is 21145306603. The reversal of 21145306577 is 77560354112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15983027776 + 5162278801 = 126424^2 + 71849^2 .

It is a cyclic number.

It is not a de Polignac number, because 21145306577 - 2¹² = 21145302481 is a prime.

It is a super-4 number, since 4×21145306577⁴ (a number of 42 digits) contains 4444 as substring.

It is not a weakly prime, because it can be changed into another prime (21145306177) 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, 10572653288 + 10572653289.

It is an arithmetic number, because the mean of its divisors is an integer number (10572653289).

Almost surely, 2^21145306577 is an apocalyptic number.

It is an amenable number.

21145306577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21145306577 is an equidigital number, since it uses as much as digits as its factorization.

21145306577 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 176400, while the sum is 41.

The spelling of 21145306577 in words is "twenty-one billion, one hundred forty-five million, three hundred six thousand, five hundred seventy-seven".