20781691904 has 44 divisors (see below), whose sum is σ = 41561698464. Its totient is φ = 10386192384.

The previous prime is 20781691891. The next prime is 20781691927. The reversal of 20781691904 is 40919618702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4035059 + ... + 4040205.

It is an arithmetic number, because the mean of its divisors is an integer number (944584056).

Almost surely, 2^20781691904 is an apocalyptic number.

It is an amenable number.

20781691904 is a deficient number, since it is larger than the sum of its proper divisors (20780006560).

20781691904 is an equidigital number, since it uses as much as digits as its factorization.

20781691904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9110 (or 9092 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 47.

The spelling of 20781691904 in words is "twenty billion, seven hundred eighty-one million, six hundred ninety-one thousand, nine hundred four".