20780306 has 4 divisors (see below), whose sum is σ = 31170462. Its totient is φ = 10390152.

The previous prime is 20780303. The next prime is 20780329. The reversal of 20780306 is 60308702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14753281 + 6027025 = 3841^2 + 2455^2 .

It is a super-2 number, since 2×20780306² = 863642234907272, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20780303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5195075 + ... + 5195078.

Almost surely, 2^20780306 is an apocalyptic number.

20780306 is a deficient number, since it is larger than the sum of its proper divisors (10390156).

20780306 is a wasteful number, since it uses less digits than its factorization.

20780306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10390155.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 20780306 is about 4558.5420915025. The cubic root of 20780306 is about 274.9269491916.

The spelling of 20780306 in words is "twenty million, seven hundred eighty thousand, three hundred six".