20851541 has 2 divisors, whose sum is σ = 20851542. Its totient is φ = 20851540.

The previous prime is 20851513. The next prime is 20851549. The reversal of 20851541 is 14515802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20295025 + 556516 = 4505^2 + 746^2 .

It is a cyclic number.

It is not a de Polignac number, because 20851541 - 2⁶ = 20851477 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20851541.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20851549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425770 + 10425771.

It is an arithmetic number, because the mean of its divisors is an integer number (10425771).

Almost surely, 2^20851541 is an apocalyptic number.

It is an amenable number.

20851541 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851541 is an equidigital number, since it uses as much as digits as its factorization.

20851541 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 20851541 is about 4566.3487602241. The cubic root of 20851541 is about 275.2407412542.

The spelling of 20851541 in words is "twenty million, eight hundred fifty-one thousand, five hundred forty-one".