21540677 has 2 divisors, whose sum is σ = 21540678. Its totient is φ = 21540676.

The previous prime is 21540653. The next prime is 21540679. The reversal of 21540677 is 77604512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18671041 + 2869636 = 4321^2 + 1694^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540677 - 2¹⁰ = 21539653 is a prime.

Together with 21540679, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1361984 and since 21540677 and 1361984 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 (21540679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770338 + 10770339.

It is an arithmetic number, because the mean of its divisors is an integer number (10770339).

Almost surely, 2^21540677 is an apocalyptic number.

It is an amenable number.

21540677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540677 is an equidigital number, since it uses as much as digits as its factorization.

21540677 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11760, while the sum is 32.

The square root of 21540677 is about 4641.1934887483. The cubic root of 21540677 is about 278.2401397951.

The spelling of 21540677 in words is "twenty-one million, five hundred forty thousand, six hundred seventy-seven".