21139087 has 2 divisors, whose sum is σ = 21139088. Its totient is φ = 21139086.

The previous prime is 21139061. The next prime is 21139091. The reversal of 21139087 is 78093112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21139087 - 2⁷ = 21138959 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10569543 + 10569544.

It is an arithmetic number, because the mean of its divisors is an integer number (10569544).

Almost surely, 2^21139087 is an apocalyptic number.

21139087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21139087 is an equidigital number, since it uses as much as digits as its factorization.

21139087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21139087 is about 4597.7262858939. The cubic root of 21139087 is about 276.5001738557.

The spelling of 21139087 in words is "twenty-one million, one hundred thirty-nine thousand, eighty-seven".