21055739 has 2 divisors, whose sum is σ = 21055740. Its totient is φ = 21055738.

The previous prime is 21055733. The next prime is 21055759. The reversal of 21055739 is 93755012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21055739 - 2¹² = 21051643 is a prime.

It is a super-2 number, since 2×21055739² = 886688289672242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21055733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527869 + 10527870.

It is an arithmetic number, because the mean of its divisors is an integer number (10527870).

Almost surely, 2^21055739 is an apocalyptic number.

21055739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055739 is an equidigital number, since it uses as much as digits as its factorization.

21055739 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9450, while the sum is 32.

The square root of 21055739 is about 4588.6532882753. The cubic root of 21055739 is about 276.1362967159.

The spelling of 21055739 in words is "twenty-one million, fifty-five thousand, seven hundred thirty-nine".