21203057677 has 2 divisors, whose sum is σ = 21203057678. Its totient is φ = 21203057676.

The previous prime is 21203057663. The next prime is 21203057699. The reversal of 21203057677 is 77675030212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18305819401 + 2897238276 = 135299^2 + 53826^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203057677 - 2²⁷ = 21068839949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21203057647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601528838 + 10601528839.

It is an arithmetic number, because the mean of its divisors is an integer number (10601528839).

Almost surely, 2^21203057677 is an apocalyptic number.

It is an amenable number.

21203057677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203057677 is an equidigital number, since it uses as much as digits as its factorization.

21203057677 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 123480, while the sum is 40.

Adding to 21203057677 its reverse (77675030212), we get a palindrome (98878087889).

The spelling of 21203057677 in words is "twenty-one billion, two hundred three million, fifty-seven thousand, six hundred seventy-seven".