651881 has 2 divisors, whose sum is σ = 651882. Its totient is φ = 651880.

The previous prime is 651877. The next prime is 651901. The reversal of 651881 is 188156.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 11881 = 800^2 + 109^2 .

It is a cyclic number.

It is not a de Polignac number, because 651881 - 2² = 651877 is a prime.

It is a super-2 number, since 2×651881² = 849897676322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (651811) 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 as a sum of consecutive naturals, namely, 325940 + 325941.

It is an arithmetic number, because the mean of its divisors is an integer number (325941).

2⁶⁵¹⁸⁸¹ is an apocalyptic number.

It is an amenable number.

651881 is a deficient number, since it is larger than the sum of its proper divisors (1).

651881 is an equidigital number, since it uses as much as digits as its factorization.

651881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1920, while the sum is 29.

The square root of 651881 is about 807.3914787759. The cubic root of 651881 is about 86.7073888181.

It can be divided in two parts, 65 and 1881, that multiplied together give a triangular number (122265 = T₄₉₄).

The spelling of 651881 in words is "six hundred fifty-one thousand, eight hundred eighty-one".