21047252 has 6 divisors (see below), whose sum is σ = 36832698. Its totient is φ = 10523624.

The previous prime is 21047237. The next prime is 21047281. The reversal of 21047252 is 25274012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20830096 + 217156 = 4564^2 + 466^2 .

It is a congruent number.

It is an unprimeable number.

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, 2630903 + ... + 2630910.

It is an arithmetic number, because the mean of its divisors is an integer number (6138783).

Almost surely, 2^21047252 is an apocalyptic number.

It is an amenable number.

21047252 is a deficient number, since it is larger than the sum of its proper divisors (15785446).

21047252 is a wasteful number, since it uses less digits than its factorization.

21047252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5261817 (or 5261815 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21047252 is about 4587.7284139321. The cubic root of 21047252 is about 276.0991907009.

The spelling of 21047252 in words is "twenty-one million, forty-seven thousand, two hundred fifty-two".