51650721 has 24 divisors (see below), whose sum is σ = 78936000. Its totient is φ = 32454432.

The previous prime is 51650671. The next prime is 51650723. The reversal of 51650721 is 12705615.

51650721 is a `hidden beast` number, since 5 + 1 + 650 + 7 + 2 + 1 = 666.

It is not a de Polignac number, because 51650721 - 2¹³ = 51642529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51650723) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38500 + ... + 39818.

It is an arithmetic number, because the mean of its divisors is an integer number (3289000).

Almost surely, 2^51650721 is an apocalyptic number.

It is an amenable number.

51650721 is a deficient number, since it is larger than the sum of its proper divisors (27285279).

51650721 is a wasteful number, since it uses less digits than its factorization.

51650721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1573 (or 1570 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 51650721 is about 7186.8436048101. The cubic root of 51650721 is about 372.4135402838.

The spelling of 51650721 in words is "fifty-one million, six hundred fifty thousand, seven hundred twenty-one".