641566157 has 4 divisors (see below), whose sum is σ = 644823036. Its totient is φ = 638309280.

The previous prime is 641566151. The next prime is 641566169. The reversal of 641566157 is 751665146.

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

It can be written as a sum of positive squares in 2 ways, for example, as 522625321 + 118940836 = 22861^2 + 10906^2 .

It is a cyclic number.

It is not a de Polignac number, because 641566157 - 2¹⁴ = 641549773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641566151) 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, 1628144 + ... + 1628537.

It is an arithmetic number, because the mean of its divisors is an integer number (161205759).

Almost surely, 2^641566157 is an apocalyptic number.

It is an amenable number.

641566157 is a deficient number, since it is larger than the sum of its proper divisors (3256879).

641566157 is a wasteful number, since it uses less digits than its factorization.

641566157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3256878.

The product of its digits is 151200, while the sum is 41.

The square root of 641566157 is about 25329.1562630894. The cubic root of 641566157 is about 862.4762581716.

The spelling of 641566157 in words is "six hundred forty-one million, five hundred sixty-six thousand, one hundred fifty-seven".