21180139 has 2 divisors, whose sum is σ = 21180140. Its totient is φ = 21180138.

The previous prime is 21180101. The next prime is 21180151. The reversal of 21180139 is 93108112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21180139 is a prime.

It is not a weakly prime, because it can be changed into another prime (21180239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10590069 + 10590070.

It is an arithmetic number, because the mean of its divisors is an integer number (10590070).

Almost surely, 2^21180139 is an apocalyptic number.

21180139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21180139 is an equidigital number, since it uses as much as digits as its factorization.

21180139 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 21180139 is about 4602.1885011373. The cubic root of 21180139 is about 276.6790454293.

The spelling of 21180139 in words is "twenty-one million, one hundred eighty thousand, one hundred thirty-nine".