21983993 has 4 divisors (see below), whose sum is σ = 21997668. Its totient is φ = 21970320.

The previous prime is 21983987. The next prime is 21983999. The reversal of 21983993 is 39938912.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21983987) and next prime (21983999).

It can be written as a sum of positive squares in 2 ways, for example, as 2650384 + 19333609 = 1628^2 + 4397^2 .

It is a cyclic number.

It is not a de Polignac number, because 21983993 - 2⁴ = 21983977 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21983999) 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, 4046 + ... + 7767.

It is an arithmetic number, because the mean of its divisors is an integer number (5499417).

Almost surely, 2^21983993 is an apocalyptic number.

It is an amenable number.

21983993 is a deficient number, since it is larger than the sum of its proper divisors (13675).

21983993 is a wasteful number, since it uses less digits than its factorization.

21983993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13674.

The product of its digits is 104976, while the sum is 44.

The square root of 21983993 is about 4688.7090973956. The cubic root of 21983993 is about 280.1359586322.

The spelling of 21983993 in words is "twenty-one million, nine hundred eighty-three thousand, nine hundred ninety-three".