21583993 has 2 divisors, whose sum is σ = 21583994. Its totient is φ = 21583992.

The previous prime is 21583963. The next prime is 21583997. The reversal of 21583993 is 39938512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21132409 + 451584 = 4597^2 + 672^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21583993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21583997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10791996 + 10791997.

It is an arithmetic number, because the mean of its divisors is an integer number (10791997).

Almost surely, 2^21583993 is an apocalyptic number.

It is an amenable number.

21583993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21583993 is an equidigital number, since it uses as much as digits as its factorization.

21583993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 58320, while the sum is 40.

The square root of 21583993 is about 4645.8576172758. The cubic root of 21583993 is about 278.4265186527.

The spelling of 21583993 in words is "twenty-one million, five hundred eighty-three thousand, nine hundred ninety-three".