21355066247 has 2 divisors, whose sum is σ = 21355066248. Its totient is φ = 21355066246.

The previous prime is 21355066223. The next prime is 21355066253. The reversal of 21355066247 is 74266055312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355066247 - 2³⁰ = 20281324423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21355066277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677533123 + 10677533124.

It is an arithmetic number, because the mean of its divisors is an integer number (10677533124).

Almost surely, 2^21355066247 is an apocalyptic number.

21355066247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355066247 is an equidigital number, since it uses as much as digits as its factorization.

21355066247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 302400, while the sum is 41.

The spelling of 21355066247 in words is "twenty-one billion, three hundred fifty-five million, sixty-six thousand, two hundred forty-seven".