21500212 has 6 divisors (see below), whose sum is σ = 37625378. Its totient is φ = 10750104.

The previous prime is 21500209. The next prime is 21500231. The reversal of 21500212 is 21200512.

It can be written as a sum of positive squares in only one way, i.e., 21123216 + 376996 = 4596^2 + 614^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21500192 and 21500201.

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, 2687523 + ... + 2687530.

Almost surely, 2^21500212 is an apocalyptic number.

It is an amenable number.

21500212 is a deficient number, since it is larger than the sum of its proper divisors (16125166).

21500212 is a wasteful number, since it uses less digits than its factorization.

21500212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5375057 (or 5375055 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21500212 is about 4636.8321082394. The cubic root of 21500212 is about 278.0658022728.

Adding to 21500212 its reverse (21200512), we get a palindrome (42700724).

It can be divided in two parts, 21500 and 212, that added together give a palindrome (21712).

The spelling of 21500212 in words is "twenty-one million, five hundred thousand, two hundred twelve".