21967281 has 80 divisors (see below), whose sum is σ = 41399424. Its totient is φ = 11321856.

The previous prime is 21967271. The next prime is 21967303. The reversal of 21967281 is 18276912.

It is not a de Polignac number, because 21967281 - 2¹⁰ = 21966257 is a prime.

It is a super-2 number, since 2×21967281² = 965122869065922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21967241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 414451 + ... + 414503.

Almost surely, 2^21967281 is an apocalyptic number.

21967281 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21967281 is a deficient number, since it is larger than the sum of its proper divisors (19432143).

21967281 is a wasteful number, since it uses less digits than its factorization.

21967281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 123 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21967281 is about 4686.9266049299. The cubic root of 21967281 is about 280.0649551685.

The spelling of 21967281 in words is "twenty-one million, nine hundred sixty-seven thousand, two hundred eighty-one".