661005099951 has 24 divisors (see below), whose sum is σ = 1025275028400. Its totient is φ = 377701494912.

The previous prime is 661005099949. The next prime is 661005099983. The reversal of 661005099951 is 159990500166.

It is a happy number.

It is not a de Polignac number, because 661005099951 - 2¹ = 661005099949 is a prime.

It is a super-2 number, since 2×661005099951² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661005099894 and 661005099903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661005099901) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4087995 + ... + 4246611.

It is an arithmetic number, because the mean of its divisors is an integer number (42719792850).

Almost surely, 2^661005099951 is an apocalyptic number.

661005099951 is a deficient number, since it is larger than the sum of its proper divisors (364269928449).

661005099951 is a wasteful number, since it uses less digits than its factorization.

661005099951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186983 (or 186976 counting only the distinct ones).

The product of its (nonzero) digits is 656100, while the sum is 51.

The spelling of 661005099951 in words is "six hundred sixty-one billion, five million, ninety-nine thousand, nine hundred fifty-one".