21210704 has 10 divisors (see below), whose sum is σ = 41095770. Its totient is φ = 10605344.

The previous prime is 21210703. The next prime is 21210719. The reversal of 21210704 is 40701212.

It can be written as a sum of positive squares in only one way, i.e., 20720704 + 490000 = 4552^2 + 700^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 662819 + ... + 662850.

It is an arithmetic number, because the mean of its divisors is an integer number (4109577).

Almost surely, 2^21210704 is an apocalyptic number.

It is an amenable number.

21210704 is a deficient number, since it is larger than the sum of its proper divisors (19885066).

21210704 is a wasteful number, since it uses less digits than its factorization.

21210704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1325677 (or 1325671 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 21210704 is about 4605.5080067241. The cubic root of 21210704 is about 276.8120730475.

Adding to 21210704 its reverse (40701212), we get a palindrome (61911916).

The spelling of 21210704 in words is "twenty-one million, two hundred ten thousand, seven hundred four".