661533394 has 4 divisors (see below), whose sum is σ = 992300094. Its totient is φ = 330766696.

The previous prime is 661533391. The next prime is 661533409. The reversal of 661533394 is 493335166.

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

It can be written as a sum of positive squares in only one way, i.e., 421686225 + 239847169 = 20535^2 + 15487^2 .

It is not an unprimeable number, because it can be changed into a prime (661533391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165383347 + ... + 165383350.

Almost surely, 2^661533394 is an apocalyptic number.

661533394 is a deficient number, since it is larger than the sum of its proper divisors (330766700).

661533394 is a wasteful number, since it uses less digits than its factorization.

661533394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330766699.

The product of its digits is 174960, while the sum is 40.

The square root of 661533394 is about 25720.2914835738. The cubic root of 661533394 is about 871.3325218128.

The spelling of 661533394 in words is "six hundred sixty-one million, five hundred thirty-three thousand, three hundred ninety-four".