20647390864 has 15 divisors (see below), whose sum is σ = 40005433443. Its totient is φ = 10323408048.

The previous prime is 20647390823. The next prime is 20647390873. The reversal of 20647390864 is 46809374602.

The square root of 20647390864 is 143692.

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

It is a Duffinian 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 2 ways as a sum of consecutive naturals, for example, 556807 + ... + 592729.

Almost surely, 2^20647390864 is an apocalyptic number.

20647390864 is the 143692-nd square number.

It is an amenable number.

20647390864 is a deficient number, since it is larger than the sum of its proper divisors (19358042579).

20647390864 is an frugal number, since it uses more digits than its factorization.

20647390864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71854 (or 35925 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 49.

Multiplying 20647390864 by its sum of digits (49), we get a square (1011722152336 = 1005844²).

The spelling of 20647390864 in words is "twenty billion, six hundred forty-seven million, three hundred ninety thousand, eight hundred sixty-four".