51216891 has 16 divisors (see below), whose sum is σ = 74625408. Its totient is φ = 30987200.

The previous prime is 51216889. The next prime is 51216899. The reversal of 51216891 is 19861215.

It is a cyclic number.

It is not a de Polignac number, because 51216891 - 2¹ = 51216889 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (51216899) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27376 + ... + 29186.

It is an arithmetic number, because the mean of its divisors is an integer number (4664088).

Almost surely, 2^51216891 is an apocalyptic number.

51216891 is a deficient number, since it is larger than the sum of its proper divisors (23408517).

51216891 is a wasteful number, since it uses less digits than its factorization.

51216891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2682.

The product of its digits is 4320, while the sum is 33.

The square root of 51216891 is about 7156.5977251764. The cubic root of 51216891 is about 371.3679360937.

The spelling of 51216891 in words is "fifty-one million, two hundred sixteen thousand, eight hundred ninety-one".