20509391512 has 8 divisors (see below), whose sum is σ = 38455109100. Its totient is φ = 10254695752.

The previous prime is 20509391477. The next prime is 20509391533. The reversal of 20509391512 is 21519390502.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×20509391512² (a number of 21 digits) contains 22 as substring.

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 as a sum of consecutive naturals, namely, 1281836962 + ... + 1281836977.

Almost surely, 2^20509391512 is an apocalyptic number.

It is an amenable number.

20509391512 is a deficient number, since it is larger than the sum of its proper divisors (17945717588).

20509391512 is a wasteful number, since it uses less digits than its factorization.

20509391512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2563673945 (or 2563673941 counting only the distinct ones).

The product of its (nonzero) digits is 24300, while the sum is 37.

The spelling of 20509391512 in words is "twenty billion, five hundred nine million, three hundred ninety-one thousand, five hundred twelve".