51981239420 has 36 divisors (see below), whose sum is σ = 119986453272. Its totient is φ = 18902268000.

The previous prime is 51981239413. The next prime is 51981239449. The reversal of 51981239420 is 2493218915.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10737506 + ... + 10742345.

Almost surely, 2^51981239420 is an apocalyptic number.

It is an amenable number.

51981239420 is an abundant number, since it is smaller than the sum of its proper divisors (68005213852).

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

51981239420 is a wasteful number, since it uses less digits than its factorization.

51981239420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21479882 (or 21479869 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 44.

The spelling of 51981239420 in words is "fifty-one billion, nine hundred eighty-one million, two hundred thirty-nine thousand, four hundred twenty".