6400729 has 4 divisors (see below), whose sum is σ = 6462976. Its totient is φ = 6338484.

The previous prime is 6400717. The next prime is 6400753. The reversal of 6400729 is 9270046.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9270046 = 2 ⋅4635023.

It is a cyclic number.

It is not a de Polignac number, because 6400729 - 2⁵ = 6400697 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6400697 and 6400706.

It is not an unprimeable number, because it can be changed into a prime (6400759) 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, 30969 + ... + 31174.

It is an arithmetic number, because the mean of its divisors is an integer number (1615744).

Almost surely, 2^6400729 is an apocalyptic number.

It is an amenable number.

6400729 is a deficient number, since it is larger than the sum of its proper divisors (62247).

6400729 is a wasteful number, since it uses less digits than its factorization.

6400729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62246.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 6400729 is about 2529.9662053079. The cubic root of 6400729 is about 185.6706024899.

It can be divided in two parts, 6400 and 729, that multiplied together give a square (4665600 = 2160²).

The spelling of 6400729 in words is "six million, four hundred thousand, seven hundred twenty-nine".