661151551 has 4 divisors (see below), whose sum is σ = 664804504. Its totient is φ = 657498600.

The previous prime is 661151549. The next prime is 661151563. The reversal of 661151551 is 155151166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661151551 - 2¹ = 661151549 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 (661154551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1826205 + ... + 1826566.

It is an arithmetic number, because the mean of its divisors is an integer number (166201126).

Almost surely, 2^661151551 is an apocalyptic number.

661151551 is a deficient number, since it is larger than the sum of its proper divisors (3652953).

661151551 is a wasteful number, since it uses less digits than its factorization.

661151551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3652952.

The product of its digits is 4500, while the sum is 31.

The square root of 661151551 is about 25712.8674208070. The cubic root of 661151551 is about 871.1648425682.

The spelling of 661151551 in words is "six hundred sixty-one million, one hundred fifty-one thousand, five hundred fifty-one".