651551 has 4 divisors (see below), whose sum is σ = 658104. Its totient is φ = 645000.

The previous prime is 651517. The next prime is 651587. The reversal of 651551 is 155156.

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 651551 - 2⁶ = 651487 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 (651251) 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, 3125 + ... + 3326.

It is an arithmetic number, because the mean of its divisors is an integer number (164526).

2⁶⁵¹⁵⁵¹ is an apocalyptic number.

651551 is a deficient number, since it is larger than the sum of its proper divisors (6553).

651551 is a wasteful number, since it uses less digits than its factorization.

651551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6552.

The product of its digits is 750, while the sum is 23.

The square root of 651551 is about 807.1870910762. The cubic root of 651551 is about 86.6927551309.

It can be divided in two parts, 65155 and 1, that added together give a palindrome (65156).

The spelling of 651551 in words is "six hundred fifty-one thousand, five hundred fifty-one".