20511649 has 2 divisors, whose sum is σ = 20511650. Its totient is φ = 20511648.

The previous prime is 20511641. The next prime is 20511661. The reversal of 20511649 is 94611502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16483600 + 4028049 = 4060^2 + 2007^2 .

It is a cyclic number.

It is not a de Polignac number, because 20511649 - 2³ = 20511641 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20511641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10255824 + 10255825.

It is an arithmetic number, because the mean of its divisors is an integer number (10255825).

Almost surely, 2^20511649 is an apocalyptic number.

It is an amenable number.

20511649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20511649 is an equidigital number, since it uses as much as digits as its factorization.

20511649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 20511649 is about 4528.9788032182. The cubic root of 20511649 is about 273.7370139027.

The spelling of 20511649 in words is "twenty million, five hundred eleven thousand, six hundred forty-nine".