661772799 has 12 divisors (see below), whose sum is σ = 956995416. Its totient is φ = 440673552.

The previous prime is 661772791. The next prime is 661772803. The reversal of 661772799 is 997277166.

It is a happy number.

It is not a de Polignac number, because 661772799 - 2³ = 661772791 is a prime.

It is a super-3 number, since 3×661772799³ (a number of 27 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661772791) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34029 + ... + 49814.

It is an arithmetic number, because the mean of its divisors is an integer number (79749618).

Almost surely, 2^661772799 is an apocalyptic number.

661772799 is a deficient number, since it is larger than the sum of its proper divisors (295222617).

661772799 is a wasteful number, since it uses less digits than its factorization.

661772799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84726 (or 84723 counting only the distinct ones).

The product of its digits is 2000376, while the sum is 54.

The square root of 661772799 is about 25724.9450728277. The cubic root of 661772799 is about 871.4376191546.

The spelling of 661772799 in words is "six hundred sixty-one million, seven hundred seventy-two thousand, seven hundred ninety-nine".