20491349904 has 135 divisors (see below), whose sum is σ = 58469622939. Its totient is φ = 6699326400.

The previous prime is 20491349899. The next prime is 20491349929. The reversal of 20491349904 is 40994319402.

The square root of 20491349904 is 143148.

It is a perfect power (a square), and thus also a powerful number.

It is a self number, because there is not a number n which added to its sum of digits gives 20491349904.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 135704229 + ... + 135704379.

Almost surely, 2^20491349904 is an apocalyptic number.

20491349904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

20491349904 is the 143148-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20491349904

20491349904 is an abundant number, since it is smaller than the sum of its proper divisors (37978273035).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20491349904 is an equidigital number, since it uses as much as digits as its factorization.

20491349904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474 (or 235 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The spelling of 20491349904 in words is "twenty billion, four hundred ninety-one million, three hundred forty-nine thousand, nine hundred four".