21897693 has 6 divisors (see below), whose sum is σ = 31630014. Its totient is φ = 14598456.

The previous prime is 21897661. The next prime is 21897703. The reversal of 21897693 is 39679812.

It can be written as a sum of positive squares in only one way, i.e., 15069924 + 6827769 = 3882^2 + 2613^2 .

It is not a de Polignac number, because 21897693 - 2⁵ = 21897661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897193) 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 5 ways as a sum of consecutive naturals, for example, 1216530 + ... + 1216547.

It is an arithmetic number, because the mean of its divisors is an integer number (5271669).

Almost surely, 2^21897693 is an apocalyptic number.

It is an amenable number.

21897693 is a deficient number, since it is larger than the sum of its proper divisors (9732321).

21897693 is a wasteful number, since it uses less digits than its factorization.

21897693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2433083 (or 2433080 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 21897693 is about 4679.4970883632. The cubic root of 21897693 is about 279.7689122238.

The spelling of 21897693 in words is "twenty-one million, eight hundred ninety-seven thousand, six hundred ninety-three".