21009710 has 16 divisors (see below), whose sum is σ = 38840256. Its totient is φ = 8176608.

The previous prime is 21009701. The next prime is 21009719. The reversal of 21009710 is 1790012.

It is an interprime number because it is at equal distance from previous prime (21009701) and next prime (21009719).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21009719) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28022 + ... + 28761.

It is an arithmetic number, because the mean of its divisors is an integer number (2427516).

Almost surely, 2^21009710 is an apocalyptic number.

21009710 is a deficient number, since it is larger than the sum of its proper divisors (17830546).

21009710 is a wasteful number, since it uses less digits than its factorization.

21009710 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56827.

The product of its (nonzero) digits is 126, while the sum is 20.

The square root of 21009710 is about 4583.6350203741. The cubic root of 21009710 is about 275.9349335522.

Adding to 21009710 its reverse (1790012), we get a palindrome (22799722).

The spelling of 21009710 in words is "twenty-one million, nine thousand, seven hundred ten".