21993677 has 2 divisors, whose sum is σ = 21993678. Its totient is φ = 21993676.

The previous prime is 21993667. The next prime is 21993691. The reversal of 21993677 is 77639912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11874916 + 10118761 = 3446^2 + 3181^2 .

It is a cyclic number.

It is not a de Polignac number, because 21993677 - 2⁶ = 21993613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21993637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10996838 + 10996839.

It is an arithmetic number, because the mean of its divisors is an integer number (10996839).

Almost surely, 2^21993677 is an apocalyptic number.

It is an amenable number.

21993677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21993677 is an equidigital number, since it uses as much as digits as its factorization.

21993677 is an evil number, because the sum of its binary digits is even.

The product of its digits is 142884, while the sum is 44.

The square root of 21993677 is about 4689.7416773208. The cubic root of 21993677 is about 280.1770861075.

The spelling of 21993677 in words is "twenty-one million, nine hundred ninety-three thousand, six hundred seventy-seven".