51921870 has 288 divisors, whose sum is σ = 180247680. Its totient is φ = 9434880.

The previous prime is 51921853. The next prime is 51921899. The reversal of 51921870 is 7812915.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 2732721 + ... + 2732739.

It is an arithmetic number, because the mean of its divisors is an integer number (625860).

Almost surely, 2^51921870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51921870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90123840).

51921870 is an abundant number, since it is smaller than the sum of its proper divisors (128325810).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51921870 is a wasteful number, since it uses less digits than its factorization.

51921870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 51921870 is about 7205.6831737178. The cubic root of 51921870 is about 373.0640853790.

The spelling of 51921870 in words is "fifty-one million, nine hundred twenty-one thousand, eight hundred seventy".