21471789877 has 2 divisors, whose sum is σ = 21471789878. Its totient is φ = 21471789876.

The previous prime is 21471789869. The next prime is 21471789929. The reversal of 21471789877 is 77898717412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18216630961 + 3255158916 = 134969^2 + 57054^2 .

It is a cyclic number.

It is not a de Polignac number, because 21471789877 - 2³ = 21471789869 is a prime.

It is a super-2 number, since 2×21471789877² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21471789847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10735894938 + 10735894939.

It is an arithmetic number, because the mean of its divisors is an integer number (10735894939).

Almost surely, 2^21471789877 is an apocalyptic number.

It is an amenable number.

21471789877 is a deficient number, since it is larger than the sum of its proper divisors (1).

21471789877 is an equidigital number, since it uses as much as digits as its factorization.

21471789877 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11063808, while the sum is 61.

The spelling of 21471789877 in words is "twenty-one billion, four hundred seventy-one million, seven hundred eighty-nine thousand, eight hundred seventy-seven".