21247367653 has 2 divisors, whose sum is σ = 21247367654. Its totient is φ = 21247367652.

The previous prime is 21247367651. The next prime is 21247367657. The reversal of 21247367653 is 35676374212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21236358529 + 11009124 = 145727^2 + 3318^2 .

It is a cyclic number.

It is not a de Polignac number, because 21247367653 - 2¹ = 21247367651 is a prime.

Together with 21247367651, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21247367651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10623683826 + 10623683827.

It is an arithmetic number, because the mean of its divisors is an integer number (10623683827).

Almost surely, 2^21247367653 is an apocalyptic number.

It is an amenable number.

21247367653 is a deficient number, since it is larger than the sum of its proper divisors (1).

21247367653 is an equidigital number, since it uses as much as digits as its factorization.

21247367653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1270080, while the sum is 46.

It can be divided in two parts, 212473 and 67653, that added together give a triangular number (280126 = T₇₄₈).

The spelling of 21247367653 in words is "twenty-one billion, two hundred forty-seven million, three hundred sixty-seven thousand, six hundred fifty-three".