21645442000 has 160 divisors (see below), whose sum is σ = 64417377024. Its totient is φ = 6850368000.

The previous prime is 21645441997. The next prime is 21645442019. The reversal of 21645442000 is 24454612.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 21645442000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 122535 + ... + 241465.

Almost surely, 2^21645442000 is an apocalyptic number.

21645442000 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 21645442000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32208688512).

21645442000 is an abundant number, since it is smaller than the sum of its proper divisors (42771935024).

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

21645442000 is a wasteful number, since it uses less digits than its factorization.

21645442000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118974 (or 118958 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 28.

Adding to 21645442000 its reverse (24454612), we get a palindrome (21669896612).

The spelling of 21645442000 in words is "twenty-one billion, six hundred forty-five million, four hundred forty-two thousand".