21280077081 has 10 divisors (see below), whose sum is σ = 31788757242. Its totient is φ = 14186718000.

The previous prime is 21280077073. The next prime is 21280077101. The reversal of 21280077081 is 18077008212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15991878681 + 5288198400 = 126459^2 + 72720^2 .

It is not a de Polignac number, because 21280077081 - 2³ = 21280077073 is a prime.

It is a super-2 number, since 2×21280077081² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21280077061) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 131358420 + ... + 131358581.

Almost surely, 2^21280077081 is an apocalyptic number.

It is an amenable number.

21280077081 is a deficient number, since it is larger than the sum of its proper divisors (10508680161).

21280077081 is an equidigital number, since it uses as much as digits as its factorization.

21280077081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262717013 (or 262717004 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The spelling of 21280077081 in words is "twenty-one billion, two hundred eighty million, seventy-seven thousand, eighty-one".