21355351646723 has 2 divisors, whose sum is σ = 21355351646724. Its totient is φ = 21355351646722.

The previous prime is 21355351646687. The next prime is 21355351646749. The reversal of 21355351646723 is 32764615355312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355351646723 - 2⁸ = 21355351646467 is a prime.

It is not a weakly prime, because it can be changed into another prime (21355351646023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677675823361 + 10677675823362.

It is an arithmetic number, because the mean of its divisors is an integer number (10677675823362).

Almost surely, 2^{21355351646723} is an apocalyptic number.

21355351646723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355351646723 is an equidigital number, since it uses as much as digits as its factorization.

21355351646723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608000, while the sum is 53.

The spelling of 21355351646723 in words is "twenty-one trillion, three hundred fifty-five billion, three hundred fifty-one million, six hundred forty-six thousand, seven hundred twenty-three".