661015517 has 2 divisors, whose sum is σ = 661015518. Its totient is φ = 661015516.

The previous prime is 661015499. The next prime is 661015541. The reversal of 661015517 is 715510166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 660027481 + 988036 = 25691^2 + 994^2 .

It is a cyclic number.

It is not a de Polignac number, because 661015517 - 2¹⁴ = 660999133 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661015577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330507758 + 330507759.

It is an arithmetic number, because the mean of its divisors is an integer number (330507759).

Almost surely, 2^661015517 is an apocalyptic number.

It is an amenable number.

661015517 is a deficient number, since it is larger than the sum of its proper divisors (1).

661015517 is an equidigital number, since it uses as much as digits as its factorization.

661015517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6300, while the sum is 32.

The square root of 661015517 is about 25710.2220332692. Note that the first 3 decimals coincide. The cubic root of 661015517 is about 871.1050901727.

The spelling of 661015517 in words is "six hundred sixty-one million, fifteen thousand, five hundred seventeen".