661350091 has 4 divisors (see below), whose sum is σ = 661422952. Its totient is φ = 661277232.

The previous prime is 661350083. The next prime is 661350103. The reversal of 661350091 is 190053166.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 661350091 - 2³ = 661350083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661350061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20490 + ... + 41743.

It is an arithmetic number, because the mean of its divisors is an integer number (165355738).

Almost surely, 2^661350091 is an apocalyptic number.

661350091 is a deficient number, since it is larger than the sum of its proper divisors (72861).

661350091 is a wasteful number, since it uses less digits than its factorization.

661350091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72860.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 661350091 is about 25716.7278439540. The cubic root of 661350091 is about 871.2520357679.

The spelling of 661350091 in words is "six hundred sixty-one million, three hundred fifty thousand, ninety-one".