820216751 has 4 divisors (see below), whose sum is σ = 820848504. Its totient is φ = 819585000.

The previous prime is 820216729. The next prime is 820216759. The reversal of 820216751 is 157612028.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 820216751 - 2⁶ = 820216687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820216759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 313925 + ... + 316526.

It is an arithmetic number, because the mean of its divisors is an integer number (205212126).

Almost surely, 2^820216751 is an apocalyptic number.

820216751 is a deficient number, since it is larger than the sum of its proper divisors (631753).

820216751 is a wasteful number, since it uses less digits than its factorization.

820216751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 631752.

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 820216751 is about 28639.4265131130. The cubic root of 820216751 is about 936.0726252941.

Adding to 820216751 its reverse (157612028), we get a palindrome (977828779).

The spelling of 820216751 in words is "eight hundred twenty million, two hundred sixteen thousand, seven hundred fifty-one".