21210164 has 6 divisors (see below), whose sum is σ = 37117794. Its totient is φ = 10605080.

The previous prime is 21210151. The next prime is 21210173. The reversal of 21210164 is 46101212.

It can be written as a sum of positive squares in only one way, i.e., 18421264 + 2788900 = 4292^2 + 1670^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2651267 + ... + 2651274.

It is an arithmetic number, because the mean of its divisors is an integer number (6186299).

Almost surely, 2^21210164 is an apocalyptic number.

It is an amenable number.

21210164 is a deficient number, since it is larger than the sum of its proper divisors (15907630).

21210164 is a wasteful number, since it uses less digits than its factorization.

21210164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5302545 (or 5302543 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21210164 is about 4605.4493808965. The cubic root of 21210164 is about 276.8097239225.

Adding to 21210164 its reverse (46101212), we get a palindrome (67311376).

The spelling of 21210164 in words is "twenty-one million, two hundred ten thousand, one hundred sixty-four".