21451000 has 64 divisors (see below), whose sum is σ = 52884000. Its totient is φ = 8121600.

The previous prime is 21450971. The next prime is 21451007. The reversal of 21451000 is 15412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18436 + ... + 19564.

Almost surely, 2^21451000 is an apocalyptic number.

21451000 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 21451000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26442000).

21451000 is an abundant number, since it is smaller than the sum of its proper divisors (31433000).

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

21451000 is a wasteful number, since it uses less digits than its factorization.

21451000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1169 (or 1155 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21451000 is about 4631.5224278848. The cubic root of 21451000 is about 277.8534845499.

Adding to 21451000 its reverse (15412), we get a palindrome (21466412).

The spelling of 21451000 in words is "twenty-one million, four hundred fifty-one thousand".