661041538 has 4 divisors (see below), whose sum is σ = 991562310. Its totient is φ = 330520768.

The previous prime is 661041533. The next prime is 661041539. The reversal of 661041538 is 835140166.

It is a happy number.

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., 634384969 + 26656569 = 25187^2 + 5163^2 .

It is a super-2 number, since 2×661041538² = 873951829922810888, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661041533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165260383 + ... + 165260386.

Almost surely, 2^661041538 is an apocalyptic number.

661041538 is a deficient number, since it is larger than the sum of its proper divisors (330520772).

661041538 is a wasteful number, since it uses less digits than its factorization.

661041538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330520771.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 661041538 is about 25710.7280721492. The cubic root of 661041538 is about 871.1165204278.

The spelling of 661041538 in words is "six hundred sixty-one million, forty-one thousand, five hundred thirty-eight".