661297407 has 8 divisors (see below), whose sum is σ = 882481200. Its totient is φ = 440489280.

The previous prime is 661297367. The next prime is 661297409. The reversal of 661297407 is 704792166.

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

It is not a de Polignac number, because 661297407 - 2²⁸ = 392861951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661297409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89782 + ... + 96867.

It is an arithmetic number, because the mean of its divisors is an integer number (110310150).

Almost surely, 2^661297407 is an apocalyptic number.

661297407 is a deficient number, since it is larger than the sum of its proper divisors (221183793).

661297407 is a wasteful number, since it uses less digits than its factorization.

661297407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187833.

The product of its (nonzero) digits is 127008, while the sum is 42.

The square root of 661297407 is about 25715.7035097234. The cubic root of 661297407 is about 871.2289001338.

It can be divided in two parts, 66129 and 7407, that added together give a triangular number (73536 = T₃₈₃).

The spelling of 661297407 in words is "six hundred sixty-one million, two hundred ninety-seven thousand, four hundred seven".