21849657 has 4 divisors (see below), whose sum is σ = 29132880. Its totient is φ = 14566436.

The previous prime is 21849643. The next prime is 21849671. The reversal of 21849657 is 75694812.

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 an interprime number because it is at equal distance from previous prime (21849643) and next prime (21849671).

It is a cyclic number.

It is not a de Polignac number, because 21849657 - 2¹⁵ = 21816889 is a prime.

It is a super-2 number, since 2×21849657² = 954815022035298, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21849697) 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 3 ways as a sum of consecutive naturals, for example, 3641607 + ... + 3641612.

It is an arithmetic number, because the mean of its divisors is an integer number (7283220).

Almost surely, 2^21849657 is an apocalyptic number.

It is an amenable number.

21849657 is a deficient number, since it is larger than the sum of its proper divisors (7283223).

21849657 is an equidigital number, since it uses as much as digits as its factorization.

21849657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7283222.

The product of its digits is 120960, while the sum is 42.

The square root of 21849657 is about 4674.3616676505. The cubic root of 21849657 is about 279.5641902272.

The spelling of 21849657 in words is "twenty-one million, eight hundred forty-nine thousand, six hundred fifty-seven".