21428277 has 8 divisors (see below), whose sum is σ = 30768864. Its totient is φ = 13186608.

The previous prime is 21428243. The next prime is 21428317. The reversal of 21428277 is 77282412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21428277 - 2⁸ = 21428021 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 274683 + ... + 274760.

It is an arithmetic number, because the mean of its divisors is an integer number (3846108).

Almost surely, 2^21428277 is an apocalyptic number.

It is an amenable number.

21428277 is a deficient number, since it is larger than the sum of its proper divisors (9340587).

21428277 is a wasteful number, since it uses less digits than its factorization.

21428277 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549459.

The product of its digits is 12544, while the sum is 33.

The square root of 21428277 is about 4629.0686968331. The cubic root of 21428277 is about 277.7553400128.

The spelling of 21428277 in words is "twenty-one million, four hundred twenty-eight thousand, two hundred seventy-seven".