6451991 has 8 divisors (see below), whose sum is σ = 7941024. Its totient is φ = 5104800.

The previous prime is 6451987. The next prime is 6451997. The reversal of 6451991 is 1991546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6451991 - 2² = 6451987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6451997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35360 + ... + 35541.

It is an arithmetic number, because the mean of its divisors is an integer number (992628).

Almost surely, 2^6451991 is an apocalyptic number.

6451991 is a deficient number, since it is larger than the sum of its proper divisors (1489033).

6451991 is a wasteful number, since it uses less digits than its factorization.

6451991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70921.

The product of its digits is 9720, while the sum is 35.

The square root of 6451991 is about 2540.0769673378. The cubic root of 6451991 is about 186.1649498323.

The spelling of 6451991 in words is "six million, four hundred fifty-one thousand, nine hundred ninety-one".