21677849 has 2 divisors, whose sum is σ = 21677850. Its totient is φ = 21677848.

The previous prime is 21677833. The next prime is 21677863. The reversal of 21677849 is 94877612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17372224 + 4305625 = 4168^2 + 2075^2 .

It is a cyclic number.

It is not a de Polignac number, because 21677849 - 2⁴ = 21677833 is a prime.

It is not a weakly prime, because it can be changed into another prime (21677809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10838924 + 10838925.

It is an arithmetic number, because the mean of its divisors is an integer number (10838925).

Almost surely, 2^21677849 is an apocalyptic number.

It is an amenable number.

21677849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21677849 is an equidigital number, since it uses as much as digits as its factorization.

21677849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 44.

The square root of 21677849 is about 4655.9477015963. The cubic root of 21677849 is about 278.8295057652.

The spelling of 21677849 in words is "twenty-one million, six hundred seventy-seven thousand, eight hundred forty-nine".