21039079 has 2 divisors, whose sum is σ = 21039080. Its totient is φ = 21039078.

The previous prime is 21039001. The next prime is 21039091. The reversal of 21039079 is 97093012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21039079 - 2¹⁵ = 21006311 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21039079.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21039379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10519539 + 10519540.

It is an arithmetic number, because the mean of its divisors is an integer number (10519540).

Almost surely, 2^21039079 is an apocalyptic number.

21039079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21039079 is an equidigital number, since it uses as much as digits as its factorization.

21039079 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402, while the sum is 31.

The square root of 21039079 is about 4586.8375816024. The cubic root of 21039079 is about 276.0634480961.

The spelling of 21039079 in words is "twenty-one million, thirty-nine thousand, seventy-nine".