21967969 has 9 divisors (see below), whose sum is σ = 22698963. Its totient is φ = 21260232.

The previous prime is 21967919. The next prime is 21967987. The reversal of 21967969 is 96976912.

The square root of 21967969 is 4687.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 15311569 + 6656400 = 3913^2 + 2580^2 .

It is not a de Polignac number, because 21967969 - 2⁹ = 21967457 is a prime.

It is a super-2 number, since 2×21967969² = 965183323969922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21967909) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 201487 + ... + 201595.

It is an arithmetic number, because the mean of its divisors is an integer number (2522107).

Almost surely, 2^21967969 is an apocalyptic number.

21967969 is the 4687-th square number.

21967969 is the 2344-th centered octagonal number.

It is an amenable number.

21967969 is a deficient number, since it is larger than the sum of its proper divisors (730994).

21967969 is an frugal number, since it uses more digits than its factorization.

21967969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 152 counting only the distinct ones).

The product of its digits is 367416, while the sum is 49.

The cubic root of 21967969 is about 280.0678789513.

Multiplying 21967969 by its sum of digits (49), we get a square (1076430481 = 32809²).

The spelling of 21967969 in words is "twenty-one million, nine hundred sixty-seven thousand, nine hundred sixty-nine".