651961 has 4 divisors (see below), whose sum is σ = 673024. Its totient is φ = 630900.

The previous prime is 651943. The next prime is 651971. The reversal of 651961 is 169156.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 651961 - 2¹⁷ = 520889 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (651901) 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, 10485 + ... + 10546.

It is an arithmetic number, because the mean of its divisors is an integer number (168256).

2⁶⁵¹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

651961 is a deficient number, since it is larger than the sum of its proper divisors (21063).

651961 is a wasteful number, since it uses less digits than its factorization.

651961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21062.

The product of its digits is 1620, while the sum is 28.

The square root of 651961 is about 807.4410195178. The cubic root of 651961 is about 86.7109356349.

The spelling of 651961 in words is "six hundred fifty-one thousand, nine hundred sixty-one".