21430139 has 2 divisors, whose sum is σ = 21430140. Its totient is φ = 21430138.

The previous prime is 21430121. The next prime is 21430147. The reversal of 21430139 is 93103412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21430139 is a prime.

It is not a weakly prime, because it can be changed into another prime (21430169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715069 + 10715070.

It is an arithmetic number, because the mean of its divisors is an integer number (10715070).

Almost surely, 2^21430139 is an apocalyptic number.

21430139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21430139 is an equidigital number, since it uses as much as digits as its factorization.

21430139 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21430139 is about 4629.2698128323. The cubic root of 21430139 is about 277.7633849194.

The spelling of 21430139 in words is "twenty-one million, four hundred thirty thousand, one hundred thirty-nine".