651866 has 16 divisors (see below), whose sum is σ = 1050624. Its totient is φ = 302544.

The previous prime is 651863. The next prime is 651869. The reversal of 651866 is 668156.

It is an interprime number because it is at equal distance from previous prime (651863) and next prime (651869).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (651863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1511 + ... + 1893.

It is an arithmetic number, because the mean of its divisors is an integer number (65664).

2⁶⁵¹⁸⁶⁶ is an apocalyptic number.

651866 is a deficient number, since it is larger than the sum of its proper divisors (398758).

651866 is a wasteful number, since it uses less digits than its factorization.

651866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445.

The product of its digits is 8640, while the sum is 32.

The square root of 651866 is about 807.3821895484. The cubic root of 651866 is about 86.7067237577.

Subtracting 651866 from its reverse (668156), we obtain a triangular number (16290 = T₁₈₀).

The spelling of 651866 in words is "six hundred fifty-one thousand, eight hundred sixty-six".