20902139 has 4 divisors (see below), whose sum is σ = 21154056. Its totient is φ = 20650224.

The previous prime is 20902121. The next prime is 20902159. The reversal of 20902139 is 93120902.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20902139 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (20902159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 125834 + ... + 125999.

It is an arithmetic number, because the mean of its divisors is an integer number (5288514).

Almost surely, 2^20902139 is an apocalyptic number.

20902139 is a deficient number, since it is larger than the sum of its proper divisors (251917).

20902139 is an equidigital number, since it uses as much as digits as its factorization.

20902139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251916.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 20902139 is about 4571.8857159820. The cubic root of 20902139 is about 275.4631929422.

The spelling of 20902139 in words is "twenty million, nine hundred two thousand, one hundred thirty-nine".