51861661 has 2 divisors, whose sum is σ = 51861662. Its totient is φ = 51861660.

The previous prime is 51861643. The next prime is 51861671. The reversal of 51861661 is 16616815.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51768025 + 93636 = 7195^2 + 306^2 .

It is a cyclic number.

It is not a de Polignac number, because 51861661 - 2⁷ = 51861533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51861631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25930830 + 25930831.

It is an arithmetic number, because the mean of its divisors is an integer number (25930831).

Almost surely, 2^51861661 is an apocalyptic number.

It is an amenable number.

51861661 is a deficient number, since it is larger than the sum of its proper divisors (1).

51861661 is an equidigital number, since it uses as much as digits as its factorization.

51861661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 34.

The square root of 51861661 is about 7201.5040790102. The cubic root of 51861661 is about 372.9198269421.

The spelling of 51861661 in words is "fifty-one million, eight hundred sixty-one thousand, six hundred sixty-one".