21280877 has 4 divisors (see below), whose sum is σ = 21299040. Its totient is φ = 21262716.

The previous prime is 21280873. The next prime is 21280891. The reversal of 21280877 is 77808212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21280877 - 2² = 21280873 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7193 + ... + 9710.

It is an arithmetic number, because the mean of its divisors is an integer number (5324760).

Almost surely, 2^21280877 is an apocalyptic number.

It is an amenable number.

21280877 is a deficient number, since it is larger than the sum of its proper divisors (18163).

21280877 is a wasteful number, since it uses less digits than its factorization.

21280877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18162.

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 21280877 is about 4613.1200938194. The cubic root of 21280877 is about 277.1170032287.

The spelling of 21280877 in words is "twenty-one million, two hundred eighty thousand, eight hundred seventy-seven".