21054207 has 4 divisors (see below), whose sum is σ = 28072280. Its totient is φ = 14036136.

The previous prime is 21054199. The next prime is 21054233. The reversal of 21054207 is 70245012.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21054207 - 2³ = 21054199 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21054247) 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 in 3 ways as a sum of consecutive naturals, for example, 3509032 + ... + 3509037.

It is an arithmetic number, because the mean of its divisors is an integer number (7018070).

Almost surely, 2^21054207 is an apocalyptic number.

21054207 is a deficient number, since it is larger than the sum of its proper divisors (7018073).

21054207 is an equidigital number, since it uses as much as digits as its factorization.

21054207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7018072.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21054207 is about 4588.4863517286. The cubic root of 21054207 is about 276.1295993958.

Adding to 21054207 its reverse (70245012), we get a palindrome (91299219).

The spelling of 21054207 in words is "twenty-one million, fifty-four thousand, two hundred seven".