28155697681920 has 640 divisors, whose sum is σ = 95498527703040. Its totient is φ = 7066620887040.

The previous prime is 28155697681913. The next prime is 28155697681921. The reversal of 28155697681920 is 2918679655182.

It is a tau number, because it is divible by the number of its divisors (640).

It is a super-2 number, since 2×28155697681920² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28155697681921) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1260146269 + ... + 1260168611.

It is an arithmetic number, because the mean of its divisors is an integer number (149216449536).

Almost surely, 2^{28155697681920} is an apocalyptic number.

28155697681920 is a gapful number since it is divisible by the number (20) 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 28155697681920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47749263851520).

28155697681920 is an abundant number, since it is smaller than the sum of its proper divisors (67342830021120).

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

28155697681920 is a wasteful number, since it uses less digits than its factorization.

28155697681920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22546 (or 22530 counting only the distinct ones).

The product of its (nonzero) digits is 130636800, while the sum is 69.

The spelling of 28155697681920 in words is "twenty-eight trillion, one hundred fifty-five billion, six hundred ninety-seven million, six hundred eighty-one thousand, nine hundred twenty".