20661751504 has 20 divisors (see below), whose sum is σ = 40787468676. Its totient is φ = 10135953152.

The previous prime is 20661751493. The next prime is 20661751531. The reversal of 20661751504 is 40515716602.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18419918400 + 2241833104 = 135720^2 + 47348^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12181789 + ... + 12183484.

Almost surely, 2^20661751504 is an apocalyptic number.

It is an amenable number.

20661751504 is a deficient number, since it is larger than the sum of its proper divisors (20125717172).

20661751504 is a wasteful number, since it uses less digits than its factorization.

20661751504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24365334 (or 24365328 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 37.

It can be divided in two parts, 206617 and 51504, that added together give a triangular number (258121 = T₇₁₈).

The spelling of 20661751504 in words is "twenty billion, six hundred sixty-one million, seven hundred fifty-one thousand, five hundred four".