20440649 has 2 divisors, whose sum is σ = 20440650. Its totient is φ = 20440648.

The previous prime is 20440643. The next prime is 20440691. The reversal of 20440649 is 94604402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17073424 + 3367225 = 4132^2 + 1835^2 .

It is a cyclic number.

It is not a de Polignac number, because 20440649 - 2¹² = 20436553 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1296722 and since 20440649 and 1296722 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (20440643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10220324 + 10220325.

It is an arithmetic number, because the mean of its divisors is an integer number (10220325).

Almost surely, 2^20440649 is an apocalyptic number.

It is an amenable number.

20440649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20440649 is an equidigital number, since it uses as much as digits as its factorization.

20440649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 20440649 is about 4521.1335967874. The cubic root of 20440649 is about 273.4208066587.

The spelling of 20440649 in words is "twenty million, four hundred forty thousand, six hundred forty-nine".