651989 has 4 divisors (see below), whose sum is σ = 702156. Its totient is φ = 601824.

The previous prime is 651971. The next prime is 651997. The reversal of 651989 is 989156.

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

It can be written as a sum of positive squares in 2 ways, for example, as 209764 + 442225 = 458^2 + 665^2 .

It is a cyclic number.

It is not a de Polignac number, because 651989 - 2⁸ = 651733 is a prime.

It is a super-2 number, since 2×651989² = 850179312242, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (651289) 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, 25064 + ... + 25089.

It is an arithmetic number, because the mean of its divisors is an integer number (175539).

2⁶⁵¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

651989 is a deficient number, since it is larger than the sum of its proper divisors (50167).

651989 is a wasteful number, since it uses less digits than its factorization.

651989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50166.

The product of its digits is 19440, while the sum is 38.

The square root of 651989 is about 807.4583580594. The cubic root of 651989 is about 86.7121769522.

The spelling of 651989 in words is "six hundred fifty-one thousand, nine hundred eighty-nine".