21570436 has 6 divisors (see below), whose sum is σ = 37748270. Its totient is φ = 10785216.

The previous prime is 21570431. The next prime is 21570443. The reversal of 21570436 is 63407512.

It can be written as a sum of positive squares in only one way, i.e., 14516100 + 7054336 = 3810^2 + 2656^2 .

It is not an unprimeable number, because it can be changed into a prime (21570431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2696301 + ... + 2696308.

Almost surely, 2^21570436 is an apocalyptic number.

It is an amenable number.

21570436 is a deficient number, since it is larger than the sum of its proper divisors (16177834).

21570436 is a wasteful number, since it uses less digits than its factorization.

21570436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5392613 (or 5392611 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21570436 is about 4644.3983463954. The cubic root of 21570436 is about 278.3682128073.

Adding to 21570436 its reverse (63407512), we get a palindrome (84977948).

The spelling of 21570436 in words is "twenty-one million, five hundred seventy thousand, four hundred thirty-six".