21751172 has 6 divisors (see below), whose sum is σ = 38064558. Its totient is φ = 10875584.

The previous prime is 21751159. The next prime is 21751187. The reversal of 21751172 is 27115712.

It can be written as a sum of positive squares in only one way, i.e., 13719616 + 8031556 = 3704^2 + 2834^2 .

It is a super-2 number, since 2×21751172² = 946226966747168, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2718893 + ... + 2718900.

It is an arithmetic number, because the mean of its divisors is an integer number (6344093).

Almost surely, 2^21751172 is an apocalyptic number.

It is an amenable number.

21751172 is a deficient number, since it is larger than the sum of its proper divisors (16313386).

21751172 is a wasteful number, since it uses less digits than its factorization.

21751172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5437797 (or 5437795 counting only the distinct ones).

The product of its digits is 980, while the sum is 26.

The square root of 21751172 is about 4663.8151764409. The cubic root of 21751172 is about 279.1435222911.

Adding to 21751172 its reverse (27115712), we get a palindrome (48866884).

The spelling of 21751172 in words is "twenty-one million, seven hundred fifty-one thousand, one hundred seventy-two".