661407 has 4 divisors (see below), whose sum is σ = 881880. Its totient is φ = 440936.

The previous prime is 661393. The next prime is 661417. The reversal of 661407 is 704166.

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 661407 - 2⁶ = 661343 is a prime.

It is a D-number.

661407 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661407.

It is not an unprimeable number, because it can be changed into a prime (661417) 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, 110232 + ... + 110237.

It is an arithmetic number, because the mean of its divisors is an integer number (220470).

2⁶⁶¹⁴⁰⁷ is an apocalyptic number.

661407 is a deficient number, since it is larger than the sum of its proper divisors (220473).

661407 is a wasteful number, since it uses less digits than its factorization.

661407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220472.

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 661407 is about 813.2693280826. The cubic root of 661407 is about 87.1277025387.

The spelling of 661407 in words is "six hundred sixty-one thousand, four hundred seven".