21456170887 has 2 divisors, whose sum is σ = 21456170888. Its totient is φ = 21456170886.

The previous prime is 21456170861. The next prime is 21456170921. The reversal of 21456170887 is 78807165412.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21456170887 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21456170887.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21456170807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728085443 + 10728085444.

It is an arithmetic number, because the mean of its divisors is an integer number (10728085444).

Almost surely, 2^21456170887 is an apocalyptic number.

21456170887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456170887 is an equidigital number, since it uses as much as digits as its factorization.

21456170887 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 752640, while the sum is 49.

The spelling of 21456170887 in words is "twenty-one billion, four hundred fifty-six million, one hundred seventy thousand, eight hundred eighty-seven".