65215821 has 16 divisors (see below), whose sum is σ = 97067520. Its totient is φ = 38604720.

The previous prime is 65215819. The next prime is 65215823. The reversal of 65215821 is 12851256.

It is an interprime number because it is at equal distance from previous prime (65215819) and next prime (65215823).

It is not a de Polignac number, because 65215821 - 2¹ = 65215819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65215823) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21561 + ... + 24398.

It is an arithmetic number, because the mean of its divisors is an integer number (6066720).

Almost surely, 2^65215821 is an apocalyptic number.

It is an amenable number.

65215821 is a deficient number, since it is larger than the sum of its proper divisors (31851699).

65215821 is a wasteful number, since it uses less digits than its factorization.

65215821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46016.

The product of its digits is 4800, while the sum is 30.

The square root of 65215821 is about 8075.6313065915. The cubic root of 65215821 is about 402.5170878642.

The spelling of 65215821 in words is "sixty-five million, two hundred fifteen thousand, eight hundred twenty-one".