216778704025 has 135 divisors (see below), whose sum is σ = 318301855521. Its totient is φ = 146427765120.

The previous prime is 216778704013. The next prime is 216778704119. The reversal of 216778704025 is 520407877612.

The square root of 216778704025 is 465595.

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

It can be written as a sum of positive squares in 22 ways, for example, as 84032153689 + 132746550336 = 289883^2 + 364344^2 .

It is not a de Polignac number, because 216778704025 - 2¹¹ = 216778701977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 216778704025.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 7475127711 + ... + 7475127739.

Almost surely, 2^216778704025 is an apocalyptic number.

216778704025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

216778704025 is the 465595-th square number.

216778704025 is the 232798-th centered octagonal number.

It is an amenable number.

216778704025 is a deficient number, since it is larger than the sum of its proper divisors (101523151496).

216778704025 is an frugal number, since it uses more digits than its factorization.

216778704025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158 (or 66 counting only the distinct ones).

The product of its (nonzero) digits is 1317120, while the sum is 49.

Multiplying 216778704025 by its sum of digits (49), we get a square (10622156497225 = 3259165²).

The spelling of 216778704025 in words is "two hundred sixteen billion, seven hundred seventy-eight million, seven hundred four thousand, twenty-five".