661541405 has 12 divisors (see below), whose sum is σ = 923458140. Its totient is φ = 453628224.

The previous prime is 661541393. The next prime is 661541423. The reversal of 661541405 is 504145166.

It can be written as a sum of positive squares in 2 ways, for example, as 291248356 + 370293049 = 17066^2 + 19243^2 .

It is not a de Polignac number, because 661541405 - 2¹² = 661537309 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1349840 + ... + 1350329.

It is an arithmetic number, because the mean of its divisors is an integer number (76954845).

Almost surely, 2^661541405 is an apocalyptic number.

It is an amenable number.

661541405 is a deficient number, since it is larger than the sum of its proper divisors (261916735).

661541405 is a wasteful number, since it uses less digits than its factorization.

661541405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2700188 (or 2700181 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 32.

The square root of 661541405 is about 25720.4472161741. The cubic root of 661541405 is about 871.3360390032.

The spelling of 661541405 in words is "six hundred sixty-one million, five hundred forty-one thousand, four hundred five".