21757897 has 8 divisors (see below), whose sum is σ = 24920000. Its totient is φ = 18609264.

The previous prime is 21757873. The next prime is 21757951. The reversal of 21757897 is 79875712.

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 21757897 - 2¹⁹ = 21233609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21757837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 379 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (3115000).

Almost surely, 2^21757897 is an apocalyptic number.

It is an amenable number.

21757897 is a deficient number, since it is larger than the sum of its proper divisors (3162103).

21757897 is an equidigital number, since it uses as much as digits as its factorization.

21757897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6735.

The product of its digits is 246960, while the sum is 46.

The square root of 21757897 is about 4664.5360969768. The cubic root of 21757897 is about 279.1722877411.

The spelling of 21757897 in words is "twenty-one million, seven hundred fifty-seven thousand, eight hundred ninety-seven".