21407272 has 8 divisors (see below), whose sum is σ = 40138650. Its totient is φ = 10703632.

The previous prime is 21407263. The next prime is 21407293. The reversal of 21407272 is 27270412.

It can be written as a sum of positive squares in only one way, i.e., 21399876 + 7396 = 4626^2 + 86^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1337947 + ... + 1337962.

Almost surely, 2^21407272 is an apocalyptic number.

It is an amenable number.

21407272 is a deficient number, since it is larger than the sum of its proper divisors (18731378).

21407272 is a wasteful number, since it uses less digits than its factorization.

21407272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2675915 (or 2675911 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 21407272 is about 4626.7993256678. The cubic root of 21407272 is about 277.6645540809.

Adding to 21407272 its reverse (27270412), we get a palindrome (48677684).

The spelling of 21407272 in words is "twenty-one million, four hundred seven thousand, two hundred seventy-two".