661423731 has 8 divisors (see below), whose sum is σ = 882692304. Its totient is φ = 440552160.

The previous prime is 661423723. The next prime is 661423751. The reversal of 661423731 is 137324166.

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

It is not a de Polignac number, because 661423731 - 2³ = 661423723 is a prime.

It is a super-2 number, since 2×661423731² = 874962703859920722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661423692 and 661423701.

It is not an unprimeable number, because it can be changed into a prime (661423751) 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, 95340 + ... + 102041.

It is an arithmetic number, because the mean of its divisors is an integer number (110336538).

Almost surely, 2^661423731 is an apocalyptic number.

661423731 is a deficient number, since it is larger than the sum of its proper divisors (221268573).

661423731 is a wasteful number, since it uses less digits than its factorization.

661423731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198501.

The product of its digits is 18144, while the sum is 33.

The square root of 661423731 is about 25718.1595570134. The cubic root of 661423731 is about 871.2843719539.

Adding to 661423731 its reverse (137324166), we get a palindrome (798747897).

The spelling of 661423731 in words is "six hundred sixty-one million, four hundred twenty-three thousand, seven hundred thirty-one".