21451400 has 48 divisors (see below), whose sum is σ = 50182800. Its totient is φ = 8527680.

The previous prime is 21451373. The next prime is 21451427. The reversal of 21451400 is 415412.

It is an interprime number because it is at equal distance from previous prime (21451373) and next prime (21451427).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56411 + ... + 56789.

It is an arithmetic number, because the mean of its divisors is an integer number (1045475).

Almost surely, 2^21451400 is an apocalyptic number.

21451400 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 21451400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25091400).

21451400 is an abundant number, since it is smaller than the sum of its proper divisors (28731400).

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

21451400 is a wasteful number, since it uses less digits than its factorization.

21451400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 669 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21451400 is about 4631.5656100286. The cubic root of 21451400 is about 277.8552115976.

Adding to 21451400 its reverse (415412), we get a palindrome (21866812).

The spelling of 21451400 in words is "twenty-one million, four hundred fifty-one thousand, four hundred".