51661811 has 2 divisors, whose sum is σ = 51661812. Its totient is φ = 51661810.

The previous prime is 51661787. The next prime is 51661843. The reversal of 51661811 is 11816615.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51661811 - 2¹⁴ = 51645427 is a prime.

It is not a weakly prime, because it can be changed into another prime (51661411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25830905 + 25830906.

It is an arithmetic number, because the mean of its divisors is an integer number (25830906).

Almost surely, 2^51661811 is an apocalyptic number.

51661811 is a deficient number, since it is larger than the sum of its proper divisors (1).

51661811 is an equidigital number, since it uses as much as digits as its factorization.

51661811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 29.

The square root of 51661811 is about 7187.6151121217. The cubic root of 51661811 is about 372.4401921906.

The spelling of 51661811 in words is "fifty-one million, six hundred sixty-one thousand, eight hundred eleven".