661507573 has 4 divisors (see below), whose sum is σ = 661796128. Its totient is φ = 661219020.

The previous prime is 661507507. The next prime is 661507579. The reversal of 661507573 is 375705166.

It is a happy number.

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: 375705166 = 2 ⋅187852583.

It is a cyclic number.

It is not a de Polignac number, because 661507573 - 2⁹ = 661507061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661507579) 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, 140811 + ... + 145432.

It is an arithmetic number, because the mean of its divisors is an integer number (165449032).

Almost surely, 2^661507573 is an apocalyptic number.

It is an amenable number.

661507573 is a deficient number, since it is larger than the sum of its proper divisors (288555).

661507573 is a wasteful number, since it uses less digits than its factorization.

661507573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288554.

The product of its (nonzero) digits is 132300, while the sum is 40.

The square root of 661507573 is about 25719.7895209117. The cubic root of 661507573 is about 871.3211850358.

The spelling of 661507573 in words is "six hundred sixty-one million, five hundred seven thousand, five hundred seventy-three".