21047146 has 4 divisors (see below), whose sum is σ = 31570722. Its totient is φ = 10523572.

The previous prime is 21047119. The next prime is 21047149. The reversal of 21047146 is 64174012.

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

It can be written as a sum of positive squares in only one way, i.e., 19580625 + 1466521 = 4425^2 + 1211^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21047146.

It is not an unprimeable number, because it can be changed into a prime (21047149) 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, 5261785 + ... + 5261788.

Almost surely, 2^21047146 is an apocalyptic number.

21047146 is a deficient number, since it is larger than the sum of its proper divisors (10523576).

21047146 is a wasteful number, since it uses less digits than its factorization.

21047146 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10523575.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21047146 is about 4587.7168613593. The cubic root of 21047146 is about 276.0987271952.

The spelling of 21047146 in words is "twenty-one million, forty-seven thousand, one hundred forty-six".