21917361 has 16 divisors (see below), whose sum is σ = 29888960. Its totient is φ = 14281920.

The previous prime is 21917351. The next prime is 21917419. The reversal of 21917361 is 16371912.

It is not a de Polignac number, because 21917361 - 2¹⁰ = 21916337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21917351) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41646 + ... + 42168.

It is an arithmetic number, because the mean of its divisors is an integer number (1868060).

Almost surely, 2^21917361 is an apocalyptic number.

It is an amenable number.

21917361 is a deficient number, since it is larger than the sum of its proper divisors (7971599).

21917361 is a wasteful number, since it uses less digits than its factorization.

21917361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816.

The product of its digits is 2268, while the sum is 30.

The square root of 21917361 is about 4681.5981245724. The cubic root of 21917361 is about 279.8526478085.

The spelling of 21917361 in words is "twenty-one million, nine hundred seventeen thousand, three hundred sixty-one".