661504073 has 2 divisors, whose sum is σ = 661504074. Its totient is φ = 661504072.

The previous prime is 661504043. The next prime is 661504091. The reversal of 661504073 is 370405166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 659873344 + 1630729 = 25688^2 + 1277^2 .

It is a cyclic number.

It is not a de Polignac number, because 661504073 - 2¹⁰ = 661503049 is a prime.

It is not a weakly prime, because it can be changed into another prime (661504003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330752036 + 330752037.

It is an arithmetic number, because the mean of its divisors is an integer number (330752037).

Almost surely, 2^661504073 is an apocalyptic number.

It is an amenable number.

661504073 is a deficient number, since it is larger than the sum of its proper divisors (1).

661504073 is an equidigital number, since it uses as much as digits as its factorization.

661504073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15120, while the sum is 32.

The square root of 661504073 is about 25719.7214798294. The cubic root of 661504073 is about 871.3196483290.

The spelling of 661504073 in words is "six hundred sixty-one million, five hundred four thousand, seventy-three".