20998739 has 2 divisors, whose sum is σ = 20998740. Its totient is φ = 20998738.

The previous prime is 20998729. The next prime is 20998771. The reversal of 20998739 is 93789902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20998739 - 2¹⁶ = 20933203 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20998693 and 20998702.

It is not a weakly prime, because it can be changed into another prime (20998729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10499369 + 10499370.

It is an arithmetic number, because the mean of its divisors is an integer number (10499370).

Almost surely, 2^20998739 is an apocalyptic number.

20998739 is a deficient number, since it is larger than the sum of its proper divisors (1).

20998739 is an equidigital number, since it uses as much as digits as its factorization.

20998739 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 244944, while the sum is 47.

The square root of 20998739 is about 4582.4381065106. The cubic root of 20998739 is about 275.8868953000.

The spelling of 20998739 in words is "twenty million, nine hundred ninety-eight thousand, seven hundred thirty-nine".