21536939 has 2 divisors, whose sum is σ = 21536940. Its totient is φ = 21536938.

The previous prime is 21536929. The next prime is 21536953. The reversal of 21536939 is 93963512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21536939 - 2¹² = 21532843 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21536929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768469 + 10768470.

It is an arithmetic number, because the mean of its divisors is an integer number (10768470).

Almost surely, 2^21536939 is an apocalyptic number.

21536939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21536939 is an equidigital number, since it uses as much as digits as its factorization.

21536939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 38.

The square root of 21536939 is about 4640.7907731334. The cubic root of 21536939 is about 278.2240443274.

The spelling of 21536939 in words is "twenty-one million, five hundred thirty-six thousand, nine hundred thirty-nine".