21261400 has 24 divisors (see below), whose sum is σ = 49433220. Its totient is φ = 8504480.

The previous prime is 21261377. The next prime is 21261403. The reversal of 21261400 is 416212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261403) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 52954 + ... + 53353.

Almost surely, 2^21261400 is an apocalyptic number.

21261400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21261400 is an abundant number, since it is smaller than the sum of its proper divisors (28171820).

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

21261400 is a wasteful number, since it uses less digits than its factorization.

21261400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106323 (or 106314 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21261400 is about 4611.0085664635. The cubic root of 21261400 is about 277.0324350451.

Adding to 21261400 its reverse (416212), we get a palindrome (21677612).

The spelling of 21261400 in words is "twenty-one million, two hundred sixty-one thousand, four hundred".