21154387 has 2 divisors, whose sum is σ = 21154388. Its totient is φ = 21154386.

The previous prime is 21154381. The next prime is 21154403. The reversal of 21154387 is 78345112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21154387 - 2¹⁵ = 21121619 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21154381) 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, 10577193 + 10577194.

It is an arithmetic number, because the mean of its divisors is an integer number (10577194).

Almost surely, 2^21154387 is an apocalyptic number.

21154387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154387 is an equidigital number, since it uses as much as digits as its factorization.

21154387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 31.

The square root of 21154387 is about 4599.3898508389. The cubic root of 21154387 is about 276.5668659891.

Adding to 21154387 its reverse (78345112), we get a palindrome (99499499).

The spelling of 21154387 in words is "twenty-one million, one hundred fifty-four thousand, three hundred eighty-seven".