21398693 has 4 divisors (see below), whose sum is σ = 22524960. Its totient is φ = 20272428.

The previous prime is 21398687. The next prime is 21398701. The reversal of 21398693 is 39689312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21398693 - 2⁸ = 21398437 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21398693.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21398603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563105 + ... + 563142.

It is an arithmetic number, because the mean of its divisors is an integer number (5631240).

Almost surely, 2^21398693 is an apocalyptic number.

It is an amenable number.

21398693 is a deficient number, since it is larger than the sum of its proper divisors (1126267).

21398693 is a wasteful number, since it uses less digits than its factorization.

21398693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1126266.

The product of its digits is 69984, while the sum is 41.

The square root of 21398693 is about 4625.8721339873. The cubic root of 21398693 is about 277.6274576137.

The spelling of 21398693 in words is "twenty-one million, three hundred ninety-eight thousand, six hundred ninety-three".