21156428071 has 2 divisors, whose sum is σ = 21156428072. Its totient is φ = 21156428070.

The previous prime is 21156428057. The next prime is 21156428101. The reversal of 21156428071 is 17082465112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21156428071 - 2¹⁷ = 21156296999 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21156428071.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21156428021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578214035 + 10578214036.

It is an arithmetic number, because the mean of its divisors is an integer number (10578214036).

Almost surely, 2^21156428071 is an apocalyptic number.

21156428071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156428071 is an equidigital number, since it uses as much as digits as its factorization.

21156428071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 37.

The spelling of 21156428071 in words is "twenty-one billion, one hundred fifty-six million, four hundred twenty-eight thousand, seventy-one".