21728377 has 8 divisors (see below), whose sum is σ = 24029280. Its totient is φ = 19481760.

The previous prime is 21728347. The next prime is 21728393. The reversal of 21728377 is 77382712.

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

It is a cyclic number.

It is not a de Polignac number, because 21728377 - 2⁷ = 21728249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21728327) 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, 12727 + ... + 14332.

It is an arithmetic number, because the mean of its divisors is an integer number (3003660).

Almost surely, 2^21728377 is an apocalyptic number.

It is an amenable number.

21728377 is a deficient number, since it is larger than the sum of its proper divisors (2300903).

21728377 is a wasteful number, since it uses less digits than its factorization.

21728377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27143.

The product of its digits is 32928, while the sum is 37.

The square root of 21728377 is about 4661.3707211506. The cubic root of 21728377 is about 279.0459750463.

The spelling of 21728377 in words is "twenty-one million, seven hundred twenty-eight thousand, three hundred seventy-seven".