661443951 has 16 divisors (see below), whose sum is σ = 1008403200. Its totient is φ = 377784768.

The previous prime is 661443949. The next prime is 661443967. The reversal of 661443951 is 159344166.

It is not a de Polignac number, because 661443951 - 2¹ = 661443949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661443911) 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 15 ways as a sum of consecutive naturals, for example, 45235 + ... + 58043.

It is an arithmetic number, because the mean of its divisors is an integer number (63025200).

Almost surely, 2^661443951 is an apocalyptic number.

661443951 is a deficient number, since it is larger than the sum of its proper divisors (346959249).

661443951 is a wasteful number, since it uses less digits than its factorization.

661443951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15278.

The product of its digits is 77760, while the sum is 39.

The square root of 661443951 is about 25718.5526614543. The cubic root of 661443951 is about 871.2932503726.

The spelling of 661443951 in words is "six hundred sixty-one million, four hundred forty-three thousand, nine hundred fifty-one".