21617252 has 6 divisors (see below), whose sum is σ = 37830198. Its totient is φ = 10808624.

The previous prime is 21617249. The next prime is 21617273. The reversal of 21617252 is 25271612.

It can be written as a sum of positive squares in only one way, i.e., 19589476 + 2027776 = 4426^2 + 1424^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2702153 + ... + 2702160.

It is an arithmetic number, because the mean of its divisors is an integer number (6305033).

Almost surely, 2^21617252 is an apocalyptic number.

It is an amenable number.

21617252 is a deficient number, since it is larger than the sum of its proper divisors (16212946).

21617252 is a wasteful number, since it uses less digits than its factorization.

21617252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5404317 (or 5404315 counting only the distinct ones).

The product of its digits is 1680, while the sum is 26.

The square root of 21617252 is about 4649.4356646802. The cubic root of 21617252 is about 278.5694553694.

Adding to 21617252 its reverse (25271612), we get a palindrome (46888864).

The spelling of 21617252 in words is "twenty-one million, six hundred seventeen thousand, two hundred fifty-two".