21535172 has 12 divisors (see below), whose sum is σ = 38397996. Its totient is φ = 10564320.

The previous prime is 21535169. The next prime is 21535181. The reversal of 21535172 is 27153512.

It can be written as a sum of positive squares in 2 ways, for example, as 12630916 + 8904256 = 3554^2 + 2984^2 .

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50579 + ... + 51002.

It is an arithmetic number, because the mean of its divisors is an integer number (3199833).

Almost surely, 2^21535172 is an apocalyptic number.

It is an amenable number.

21535172 is a deficient number, since it is larger than the sum of its proper divisors (16862824).

21535172 is a wasteful number, since it uses less digits than its factorization.

21535172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101638 (or 101636 counting only the distinct ones).

The product of its digits is 2100, while the sum is 26.

The square root of 21535172 is about 4640.6003921906. The cubic root of 21535172 is about 278.2164351475.

Adding to 21535172 its reverse (27153512), we get a palindrome (48688684).

It can be divided in two parts, 2153517 and 2, that multiplied together give a palindrome (4307034).

The spelling of 21535172 in words is "twenty-one million, five hundred thirty-five thousand, one hundred seventy-two".