21676523809 has 2 divisors, whose sum is σ = 21676523810. Its totient is φ = 21676523808.

The previous prime is 21676523801. The next prime is 21676523849. The reversal of 21676523809 is 90832567612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21521770209 + 154753600 = 146703^2 + 12440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21676523809 - 2³ = 21676523801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21676523801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10838261904 + 10838261905.

It is an arithmetic number, because the mean of its divisors is an integer number (10838261905).

Almost surely, 2^21676523809 is an apocalyptic number.

It is an amenable number.

21676523809 is a deficient number, since it is larger than the sum of its proper divisors (1).

21676523809 is an equidigital number, since it uses as much as digits as its factorization.

21676523809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1088640, while the sum is 49.

The spelling of 21676523809 in words is "twenty-one billion, six hundred seventy-six million, five hundred twenty-three thousand, eight hundred nine".