21353939 has 2 divisors, whose sum is σ = 21353940. Its totient is φ = 21353938.

The previous prime is 21353923. The next prime is 21353951. The reversal of 21353939 is 93935312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21353939 - 2⁴ = 21353923 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21353899 and 21353908.

It is not a weakly prime, because it can be changed into another prime (21353539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10676969 + 10676970.

It is an arithmetic number, because the mean of its divisors is an integer number (10676970).

Almost surely, 2^21353939 is an apocalyptic number.

21353939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21353939 is an equidigital number, since it uses as much as digits as its factorization.

21353939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21870, while the sum is 35.

The square root of 21353939 is about 4621.0322439905. The cubic root of 21353939 is about 277.4337758266.

The spelling of 21353939 in words is "twenty-one million, three hundred fifty-three thousand, nine hundred thirty-nine".