20967521 has 2 divisors, whose sum is σ = 20967522. Its totient is φ = 20967520.

The previous prime is 20967509. The next prime is 20967539. The reversal of 20967521 is 12576902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16810000 + 4157521 = 4100^2 + 2039^2 .

It is a cyclic number.

It is not a de Polignac number, because 20967521 - 2²² = 16773217 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20963521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10483760 + 10483761.

It is an arithmetic number, because the mean of its divisors is an integer number (10483761).

Almost surely, 2^20967521 is an apocalyptic number.

It is an amenable number.

20967521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20967521 is an equidigital number, since it uses as much as digits as its factorization.

20967521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 20967521 is about 4579.0305742591. The cubic root of 20967521 is about 275.7501107586.

The spelling of 20967521 in words is "twenty million, nine hundred sixty-seven thousand, five hundred twenty-one".