51997209 has 12 divisors (see below), whose sum is σ = 76205808. Its totient is φ = 31513240.

The previous prime is 51997177. The next prime is 51997213. The reversal of 51997209 is 90279915.

It is not a de Polignac number, because 51997209 - 2⁵ = 51997177 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51997249) 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, 71259 + ... + 71984.

It is an arithmetic number, because the mean of its divisors is an integer number (6350484).

Almost surely, 2^51997209 is an apocalyptic number.

It is an amenable number.

51997209 is a deficient number, since it is larger than the sum of its proper divisors (24208599).

51997209 is a wasteful number, since it uses less digits than its factorization.

51997209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143268 (or 143257 counting only the distinct ones).

The product of its (nonzero) digits is 51030, while the sum is 42.

The square root of 51997209 is about 7210.9090273002. The cubic root of 51997209 is about 373.2444377170.

The spelling of 51997209 in words is "fifty-one million, nine hundred ninety-seven thousand, two hundred nine".