21510427 has 2 divisors, whose sum is σ = 21510428. Its totient is φ = 21510426.

The previous prime is 21510407. The next prime is 21510469. The reversal of 21510427 is 72401512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21510427 - 2¹¹ = 21508379 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21510398 and 21510407.

It is not a weakly prime, because it can be changed into another prime (21510407) 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, 10755213 + 10755214.

It is an arithmetic number, because the mean of its divisors is an integer number (10755214).

Almost surely, 2^21510427 is an apocalyptic number.

21510427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21510427 is an equidigital number, since it uses as much as digits as its factorization.

21510427 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21510427 is about 4637.9334837835. The cubic root of 21510427 is about 278.1098327293.

Adding to 21510427 its reverse (72401512), we get a palindrome (93911939).

The spelling of 21510427 in words is "twenty-one million, five hundred ten thousand, four hundred twenty-seven".