21013570 has 8 divisors (see below), whose sum is σ = 37824444. Its totient is φ = 8405424.

The previous prime is 21013549. The next prime is 21013583. The reversal of 21013570 is 7531012.

It can be written as a sum of positive squares in 2 ways, for example, as 20493729 + 519841 = 4527^2 + 721^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1050669 + ... + 1050688.

Almost surely, 2^21013570 is an apocalyptic number.

21013570 is a deficient number, since it is larger than the sum of its proper divisors (16810874).

21013570 is a wasteful number, since it uses less digits than its factorization.

21013570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2101364.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21013570 is about 4584.0560642296. The cubic root of 21013570 is about 275.9518311934.

Adding to 21013570 its reverse (7531012), we get a palindrome (28544582).

It can be divided in two parts, 2101 and 3570, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 21013570 in words is "twenty-one million, thirteen thousand, five hundred seventy".