21154187 has 2 divisors, whose sum is σ = 21154188. Its totient is φ = 21154186.

The previous prime is 21154157. The next prime is 21154193. The reversal of 21154187 is 78145112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21154187 - 2⁶ = 21154123 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21154157) 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, 10577093 + 10577094.

It is an arithmetic number, because the mean of its divisors is an integer number (10577094).

Almost surely, 2^21154187 is an apocalyptic number.

21154187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154187 is an equidigital number, since it uses as much as digits as its factorization.

21154187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2240, while the sum is 29.

The square root of 21154187 is about 4599.3681087732. The cubic root of 21154187 is about 276.5659944040.

Adding to 21154187 its reverse (78145112), we get a palindrome (99299299).

The spelling of 21154187 in words is "twenty-one million, one hundred fifty-four thousand, one hundred eighty-seven".