21010245 has 32 divisors (see below), whose sum is σ = 34836480. Its totient is φ = 10805760.

The previous prime is 21010237. The next prime is 21010259. The reversal of 21010245 is 54201012.

It is not a de Polignac number, because 21010245 - 2³ = 21010237 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 77971 + ... + 78239.

It is an arithmetic number, because the mean of its divisors is an integer number (1088640).

Almost surely, 2^21010245 is an apocalyptic number.

It is an amenable number.

21010245 is a deficient number, since it is larger than the sum of its proper divisors (13826235).

21010245 is a wasteful number, since it uses less digits than its factorization.

21010245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21010245 is about 4583.6933797976. The cubic root of 21010245 is about 275.9372757063.

Adding to 21010245 its reverse (54201012), we get a palindrome (75211257).

The spelling of 21010245 in words is "twenty-one million, ten thousand, two hundred forty-five".