21154207 has 2 divisors, whose sum is σ = 21154208. Its totient is φ = 21154206.

The previous prime is 21154193. The next prime is 21154283. The reversal of 21154207 is 70245112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21154207 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21154907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577103 + 10577104.

It is an arithmetic number, because the mean of its divisors is an integer number (10577104).

Almost surely, 2^21154207 is an apocalyptic number.

21154207 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154207 is an equidigital number, since it uses as much as digits as its factorization.

21154207 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 21154207 is about 4599.3702829844. The cubic root of 21154207 is about 276.5660815628.

Adding to 21154207 its reverse (70245112), we get a palindrome (91399319).

The spelling of 21154207 in words is "twenty-one million, one hundred fifty-four thousand, two hundred seven".