20780687 has 8 divisors (see below), whose sum is σ = 21196560. Its totient is φ = 20367360.

The previous prime is 20780659. The next prime is 20780689. The reversal of 20780687 is 78608702.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20780687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20780687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20780689) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26639 + ... + 27407.

It is an arithmetic number, because the mean of its divisors is an integer number (2649570).

Almost surely, 2^20780687 is an apocalyptic number.

20780687 is a deficient number, since it is larger than the sum of its proper divisors (415873).

20780687 is an equidigital number, since it uses as much as digits as its factorization.

20780687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1273.

The product of its (nonzero) digits is 37632, while the sum is 38.

The square root of 20780687 is about 4558.5838809876. The cubic root of 20780687 is about 274.9286294127.

The spelling of 20780687 in words is "twenty million, seven hundred eighty thousand, six hundred eighty-seven".