21013245 has 24 divisors (see below), whose sum is σ = 39735072. Its totient is φ = 10188000.

The previous prime is 21013217. The next prime is 21013249. The reversal of 21013245 is 54231012.

It is not a de Polignac number, because 21013245 - 2⁷ = 21013117 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013249) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20731 + ... + 21720.

It is an arithmetic number, because the mean of its divisors is an integer number (1655628).

Almost surely, 2^21013245 is an apocalyptic number.

It is an amenable number.

21013245 is a deficient number, since it is larger than the sum of its proper divisors (18721827).

21013245 is a wasteful number, since it uses less digits than its factorization.

21013245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42473 (or 42470 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21013245 is about 4584.0206151369. The cubic root of 21013245 is about 275.9504085443.

Adding to 21013245 its reverse (54231012), we get a palindrome (75244257).

The spelling of 21013245 in words is "twenty-one million, thirteen thousand, two hundred forty-five".