661505654 has 4 divisors (see below), whose sum is σ = 992258484. Its totient is φ = 330752826.

The previous prime is 661505641. The next prime is 661505657. The reversal of 661505654 is 456505166.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661505657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165376412 + ... + 165376415.

It is an arithmetic number, because the mean of its divisors is an integer number (248064621).

Almost surely, 2^661505654 is an apocalyptic number.

661505654 is a deficient number, since it is larger than the sum of its proper divisors (330752830).

661505654 is a wasteful number, since it uses less digits than its factorization.

661505654 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330752829.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 661505654 is about 25719.7522149806. The cubic root of 661505654 is about 871.3203424821.

The spelling of 661505654 in words is "six hundred sixty-one million, five hundred five thousand, six hundred fifty-four".