20851549 has 2 divisors, whose sum is σ = 20851550. Its totient is φ = 20851548.

The previous prime is 20851541. The next prime is 20851573. The reversal of 20851549 is 94515802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15856324 + 4995225 = 3982^2 + 2235^2 .

It is a cyclic number.

It is not a de Polignac number, because 20851549 - 2³ = 20851541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20851541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425774 + 10425775.

It is an arithmetic number, because the mean of its divisors is an integer number (10425775).

Almost surely, 2^20851549 is an apocalyptic number.

It is an amenable number.

20851549 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851549 is an equidigital number, since it uses as much as digits as its factorization.

20851549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 20851549 is about 4566.3496361974. The cubic root of 20851549 is about 275.2407764543.

The spelling of 20851549 in words is "twenty million, eight hundred fifty-one thousand, five hundred forty-nine".