21061739 has 2 divisors, whose sum is σ = 21061740. Its totient is φ = 21061738.

The previous prime is 21061717. The next prime is 21061757. The reversal of 21061739 is 93716012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21061739 - 2²⁴ = 4284523 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21061639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10530869 + 10530870.

It is an arithmetic number, because the mean of its divisors is an integer number (10530870).

Almost surely, 2^21061739 is an apocalyptic number.

21061739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21061739 is an equidigital number, since it uses as much as digits as its factorization.

21061739 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 21061739 is about 4589.3070282996. The cubic root of 21061739 is about 276.1625233016.

The spelling of 21061739 in words is "twenty-one million, sixty-one thousand, seven hundred thirty-nine".