21280276 has 6 divisors (see below), whose sum is σ = 37240490. Its totient is φ = 10640136.

The previous prime is 21280261. The next prime is 21280289. The reversal of 21280276 is 67208212.

It can be written as a sum of positive squares in only one way, i.e., 14899600 + 6380676 = 3860^2 + 2526^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2660031 + ... + 2660038.

Almost surely, 2^21280276 is an apocalyptic number.

It is an amenable number.

21280276 is a deficient number, since it is larger than the sum of its proper divisors (15960214).

21280276 is a wasteful number, since it uses less digits than its factorization.

21280276 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5320073 (or 5320071 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21280276 is about 4613.0549530653. The cubic root of 21280276 is about 277.1143944878.

Adding to 21280276 its reverse (67208212), we get a palindrome (88488488).

It can be divided in two parts, 212802 and 76, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 21280276 in words is "twenty-one million, two hundred eighty thousand, two hundred seventy-six".