21008149 has 2 divisors, whose sum is σ = 21008150. Its totient is φ = 21008148.

The previous prime is 21008083. The next prime is 21008153. The reversal of 21008149 is 94180012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15800625 + 5207524 = 3975^2 + 2282^2 .

It is a cyclic number.

It is not a de Polignac number, because 21008149 - 2⁷ = 21008021 is a prime.

It is a super-3 number, since 3×21008149³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21008179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504074 + 10504075.

It is an arithmetic number, because the mean of its divisors is an integer number (10504075).

Almost surely, 2^21008149 is an apocalyptic number.

It is an amenable number.

21008149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21008149 is an equidigital number, since it uses as much as digits as its factorization.

21008149 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21008149 is about 4583.4647375103. The cubic root of 21008149 is about 275.9280994884.

The spelling of 21008149 in words is "twenty-one million, eight thousand, one hundred forty-nine".