15857821980 has 1080 divisors, whose sum is σ = 69039742464. Its totient is φ = 3017710080.

The previous prime is 15857821943. The next prime is 15857821981. The reversal of 15857821980 is 8912875851.

15857821980 is a `hidden beast` number, since 1 + 58 + 578 + 2 + 19 + 8 + 0 = 666.

It is a super-2 number, since 2×15857821980² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15857821981) by changing a digit.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 124864677 + ... + 124864803.

Almost surely, 2^15857821980 is an apocalyptic number.

15857821980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15857821980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34519871232).

15857821980 is an abundant number, since it is smaller than the sum of its proper divisors (53181920484).

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

15857821980 is a wasteful number, since it uses less digits than its factorization.

15857821980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 1612800, while the sum is 54.

The spelling of 15857821980 in words is "fifteen billion, eight hundred fifty-seven million, eight hundred twenty-one thousand, nine hundred eighty".