661435551551 has 8 divisors (see below), whose sum is σ = 673938077904. Its totient is φ = 648933862720.

The previous prime is 661435551533. The next prime is 661435551559. The reversal of 661435551551 is 155155534166.

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

It is a cyclic number.

It is not a de Polignac number, because 661435551551 - 2²⁶ = 661368442687 is a prime.

It is a super-3 number, since 3×661435551551³ (a number of 36 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661435551496 and 661435551505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661435551559) 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, 1518536 + ... + 1904946.

It is an arithmetic number, because the mean of its divisors is an integer number (84242259738).

Almost surely, 2^661435551551 is an apocalyptic number.

661435551551 is a deficient number, since it is larger than the sum of its proper divisors (12502526353).

661435551551 is a wasteful number, since it uses less digits than its factorization.

661435551551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418761.

The product of its digits is 1350000, while the sum is 47.

The spelling of 661435551551 in words is "six hundred sixty-one billion, four hundred thirty-five million, five hundred fifty-one thousand, five hundred fifty-one".