51666021 has 12 divisors (see below), whose sum is σ = 81413280. Its totient is φ = 31312680.

The previous prime is 51666011. The next prime is 51666029. The reversal of 51666021 is 12066615.

It is a happy number.

It is not a de Polignac number, because 51666021 - 2⁵ = 51665989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51666029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 260841 + ... + 261038.

It is an arithmetic number, because the mean of its divisors is an integer number (6784440).

Almost surely, 2^51666021 is an apocalyptic number.

It is an amenable number.

51666021 is a deficient number, since it is larger than the sum of its proper divisors (29747259).

51666021 is a wasteful number, since it uses less digits than its factorization.

51666021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521896 (or 521893 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 51666021 is about 7187.9079710302. The cubic root of 51666021 is about 372.4503088228.

The spelling of 51666021 in words is "fifty-one million, six hundred sixty-six thousand, twenty-one".