641561505 has 64 divisors (see below), whose sum is σ = 1190999040. Its totient is φ = 292190976.

The previous prime is 641561483. The next prime is 641561533. The reversal of 641561505 is 505165146.

It is not a de Polignac number, because 641561505 - 2⁶ = 641561441 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 157302 + ... + 161328.

It is an arithmetic number, because the mean of its divisors is an integer number (18609360).

Almost surely, 2^641561505 is an apocalyptic number.

641561505 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

641561505 is a deficient number, since it is larger than the sum of its proper divisors (549437535).

641561505 is a wasteful number, since it uses less digits than its factorization.

641561505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4110.

The product of its (nonzero) digits is 18000, while the sum is 33.

The square root of 641561505 is about 25329.0644319920. The cubic root of 641561505 is about 862.4741735598.

The spelling of 641561505 in words is "six hundred forty-one million, five hundred sixty-one thousand, five hundred five".