20971949 has 2 divisors, whose sum is σ = 20971950. Its totient is φ = 20971948.

The previous prime is 20971919. The next prime is 20971957. The reversal of 20971949 is 94917902.

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., 12602500 + 8369449 = 3550^2 + 2893^2 .

It is a cyclic number.

It is not a de Polignac number, because 20971949 - 2¹² = 20967853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20971919) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10485974 + 10485975.

It is an arithmetic number, because the mean of its divisors is an integer number (10485975).

Almost surely, 2^20971949 is an apocalyptic number.

It is an amenable number.

20971949 is a deficient number, since it is larger than the sum of its proper divisors (1).

20971949 is an equidigital number, since it uses as much as digits as its factorization.

20971949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 20971949 is about 4579.5140571899. The cubic root of 20971949 is about 275.7695207077.

The spelling of 20971949 in words is "twenty million, nine hundred seventy-one thousand, nine hundred forty-nine".