661090894 has 4 divisors (see below), whose sum is σ = 991636344. Its totient is φ = 330545446.

The previous prime is 661090879. The next prime is 661090949. The reversal of 661090894 is 498090166.

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

It is a self number, because there is not a number n which added to its sum of digits gives 661090894.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165272722 + ... + 165272725.

It is an arithmetic number, because the mean of its divisors is an integer number (247909086).

Almost surely, 2^661090894 is an apocalyptic number.

661090894 is a deficient number, since it is larger than the sum of its proper divisors (330545450).

661090894 is a wasteful number, since it uses less digits than its factorization.

661090894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330545449.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 661090894 is about 25711.6878870291. The cubic root of 661090894 is about 871.1382002339.

The spelling of 661090894 in words is "six hundred sixty-one million, ninety thousand, eight hundred ninety-four".