21694993 has 4 divisors (see below), whose sum is σ = 21905728. Its totient is φ = 21484260.

The previous prime is 21694991. The next prime is 21694997. The reversal of 21694993 is 39949612.

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 21694993 - 2¹ = 21694991 is a prime.

It is a deceptive number, since it divides R_21694992.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21694991) 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, 105213 + ... + 105418.

It is an arithmetic number, because the mean of its divisors is an integer number (5476432).

Almost surely, 2^21694993 is an apocalyptic number.

It is an amenable number.

21694993 is a deficient number, since it is larger than the sum of its proper divisors (210735).

21694993 is a wasteful number, since it uses less digits than its factorization.

21694993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210734.

The product of its digits is 104976, while the sum is 43.

The square root of 21694993 is about 4657.7884237050. The cubic root of 21694993 is about 278.9029908150.

The spelling of 21694993 in words is "twenty-one million, six hundred ninety-four thousand, nine hundred ninety-three".