21278041 has 2 divisors, whose sum is σ = 21278042. Its totient is φ = 21278040.

The previous prime is 21278021. The next prime is 21278063. The reversal of 21278041 is 14087212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21196816 + 81225 = 4604^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 21278041 - 2¹³ = 21269849 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21277997 and 21278015.

It is not a weakly prime, because it can be changed into another prime (21278021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10639020 + 10639021.

It is an arithmetic number, because the mean of its divisors is an integer number (10639021).

Almost surely, 2^21278041 is an apocalyptic number.

It is an amenable number.

21278041 is a deficient number, since it is larger than the sum of its proper divisors (1).

21278041 is an equidigital number, since it uses as much as digits as its factorization.

21278041 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21278041 is about 4612.8126994275. The cubic root of 21278041 is about 277.1046926657.

The spelling of 21278041 in words is "twenty-one million, two hundred seventy-eight thousand, forty-one".