1661500637 has 2 divisors, whose sum is σ = 1661500638. Its totient is φ = 1661500636.

The previous prime is 1661500609. The next prime is 1661500663. The reversal of 1661500637 is 7360051661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1306027321 + 355473316 = 36139^2 + 18854^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661500637 - 2⁶ = 1661500573 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1661500597 and 1661500606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661500537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830750318 + 830750319.

It is an arithmetic number, because the mean of its divisors is an integer number (830750319).

Almost surely, 2^1661500637 is an apocalyptic number.

It is an amenable number.

1661500637 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661500637 is an equidigital number, since it uses as much as digits as its factorization.

1661500637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22680, while the sum is 35.

The square root of 1661500637 is about 40761.5092581224. The cubic root of 1661500637 is about 1184.4048325455.

The spelling of 1661500637 in words is "one billion, six hundred sixty-one million, five hundred thousand, six hundred thirty-seven".