21455117 has 2 divisors, whose sum is σ = 21455118. Its totient is φ = 21455116.

The previous prime is 21455111. The next prime is 21455143. The reversal of 21455117 is 71155412.

It is an a-pointer prime, because the next prime (21455143) can be obtained adding 21455117 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16410601 + 5044516 = 4051^2 + 2246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455117 - 2⁴ = 21455101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21455111) 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, 10727558 + 10727559.

It is an arithmetic number, because the mean of its divisors is an integer number (10727559).

Almost surely, 2^21455117 is an apocalyptic number.

It is an amenable number.

21455117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21455117 is an equidigital number, since it uses as much as digits as its factorization.

21455117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1400, while the sum is 26.

The square root of 21455117 is about 4631.9668608486. The cubic root of 21455117 is about 277.8712591621.

The spelling of 21455117 in words is "twenty-one million, four hundred fifty-five thousand, one hundred seventeen".