21542820727 has 2 divisors, whose sum is σ = 21542820728. Its totient is φ = 21542820726.

The previous prime is 21542820701. The next prime is 21542820757. The reversal of 21542820727 is 72702824512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21542820727 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21542820727.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542820757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771410363 + 10771410364.

It is an arithmetic number, because the mean of its divisors is an integer number (10771410364).

Almost surely, 2^21542820727 is an apocalyptic number.

21542820727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542820727 is an equidigital number, since it uses as much as digits as its factorization.

21542820727 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 125440, while the sum is 40.

The spelling of 21542820727 in words is "twenty-one billion, five hundred forty-two million, eight hundred twenty thousand, seven hundred twenty-seven".