20839957 has 2 divisors, whose sum is σ = 20839958. Its totient is φ = 20839956.

The previous prime is 20839939. The next prime is 20839961. The reversal of 20839957 is 75993802.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20376196 + 463761 = 4514^2 + 681^2 .

It is a cyclic number.

It is not a de Polignac number, because 20839957 - 2⁷ = 20839829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20839927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10419978 + 10419979.

It is an arithmetic number, because the mean of its divisors is an integer number (10419979).

Almost surely, 2^20839957 is an apocalyptic number.

It is an amenable number.

20839957 is a deficient number, since it is larger than the sum of its proper divisors (1).

20839957 is an equidigital number, since it uses as much as digits as its factorization.

20839957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 43.

The square root of 20839957 is about 4565.0801745424. The cubic root of 20839957 is about 275.1897621386.

The spelling of 20839957 in words is "twenty million, eight hundred thirty-nine thousand, nine hundred fifty-seven".