21307877 has 2 divisors, whose sum is σ = 21307878. Its totient is φ = 21307876.

The previous prime is 21307859. The next prime is 21307879. The reversal of 21307877 is 77870312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13293316 + 8014561 = 3646^2 + 2831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21307877 - 2⁶ = 21307813 is a prime.

Together with 21307879, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1348199 and since 21307877 and 1348199 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21307879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10653938 + 10653939.

It is an arithmetic number, because the mean of its divisors is an integer number (10653939).

Almost surely, 2^21307877 is an apocalyptic number.

It is an amenable number.

21307877 is a deficient number, since it is larger than the sum of its proper divisors (1).

21307877 is an equidigital number, since it uses as much as digits as its factorization.

21307877 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16464, while the sum is 35.

The square root of 21307877 is about 4616.0456020278. The cubic root of 21307877 is about 277.2341506094.

The spelling of 21307877 in words is "twenty-one million, three hundred seven thousand, eight hundred seventy-seven".