21542542400 has 84 divisors (see below), whose sum is σ = 53118885888. Its totient is φ = 8599011840.

The previous prime is 21542542397. The next prime is 21542542403. The reversal of 21542542400 is 424524512.

It is an interprime number because it is at equal distance from previous prime (21542542397) and next prime (21542542403).

It is a super-2 number, since 2×21542542400² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21542542403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 765377 + ... + 793023.

Almost surely, 2^21542542400 is an apocalyptic number.

21542542400 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 21542542400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26559442944).

21542542400 is an abundant number, since it is smaller than the sum of its proper divisors (31576343488).

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

21542542400 is a wasteful number, since it uses less digits than its factorization.

21542542400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28156 (or 28141 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 29.

The spelling of 21542542400 in words is "twenty-one billion, five hundred forty-two million, five hundred forty-two thousand, four hundred".