21487072688881 has 2 divisors, whose sum is σ = 21487072688882. Its totient is φ = 21487072688880.

The previous prime is 21487072688867. The next prime is 21487072688899. The reversal of 21487072688881 is 18888627078412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14772838167025 + 6714234521856 = 3843545^2 + 2591184^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21487072688881 is a prime.

It is a super-2 number, since 2×21487072688881² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21487072688881.

It is not a weakly prime, because it can be changed into another prime (21487072988881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10743536344440 + 10743536344441.

It is an arithmetic number, because the mean of its divisors is an integer number (10743536344441).

Almost surely, 2^{21487072688881} is an apocalyptic number.

It is an amenable number.

21487072688881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21487072688881 is an equidigital number, since it uses as much as digits as its factorization.

21487072688881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 154140672, while the sum is 70.

The spelling of 21487072688881 in words is "twenty-one trillion, four hundred eighty-seven billion, seventy-two million, six hundred eighty-eight thousand, eight hundred eighty-one".