21097115424 has 864 divisors, whose sum is σ = 83894952960. Its totient is φ = 4949683200.

The previous prime is 21097115407. The next prime is 21097115437. The reversal of 21097115424 is 42451179012.

21097115424 is a `hidden beast` number, since 2 + 10 + 97 + 11 + 542 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 67836229 + ... + 67836539.

It is an arithmetic number, because the mean of its divisors is an integer number (97100640).

Almost surely, 2^21097115424 is an apocalyptic number.

21097115424 is a gapful number since it is divisible by the number (24) 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 21097115424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41947476480).

21097115424 is an abundant number, since it is smaller than the sum of its proper divisors (62797837536).

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

21097115424 is a wasteful number, since it uses less digits than its factorization.

21097115424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The spelling of 21097115424 in words is "twenty-one billion, ninety-seven million, one hundred fifteen thousand, four hundred twenty-four".