20640377 has 4 divisors (see below), whose sum is σ = 20649600. Its totient is φ = 20631156.

The previous prime is 20640331. The next prime is 20640391. The reversal of 20640377 is 77304602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20640377 - 2⁶ = 20640313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1124 + ... + 6522.

It is an arithmetic number, because the mean of its divisors is an integer number (5162400).

Almost surely, 2^20640377 is an apocalyptic number.

It is an amenable number.

20640377 is a deficient number, since it is larger than the sum of its proper divisors (9223).

20640377 is an equidigital number, since it uses as much as digits as its factorization.

20640377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9222.

The product of its (nonzero) digits is 7056, while the sum is 29.

The square root of 20640377 is about 4543.1681676997. The cubic root of 20640377 is about 274.3084641219.

Adding to 20640377 its reverse (77304602), we get a palindrome (97944979).

The spelling of 20640377 in words is "twenty million, six hundred forty thousand, three hundred seventy-seven".