21210253277 has 2 divisors, whose sum is σ = 21210253278. Its totient is φ = 21210253276.

The previous prime is 21210253241. The next prime is 21210253319. The reversal of 21210253277 is 77235201212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16731163801 + 4479089476 = 129349^2 + 66926^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210253277 - 2¹⁰ = 21210252253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210253217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605126638 + 10605126639.

It is an arithmetic number, because the mean of its divisors is an integer number (10605126639).

Almost surely, 2^21210253277 is an apocalyptic number.

It is an amenable number.

21210253277 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210253277 is an equidigital number, since it uses as much as digits as its factorization.

21210253277 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11760, while the sum is 32.

Adding to 21210253277 its reverse (77235201212), we get a palindrome (98445454489).

The spelling of 21210253277 in words is "twenty-one billion, two hundred ten million, two hundred fifty-three thousand, two hundred seventy-seven".