21289400 has 48 divisors (see below), whose sum is σ = 54003240. Its totient is φ = 7740800.

The previous prime is 21289399. The next prime is 21289409. The reversal of 21289400 is 498212.

It is a self number, because there is not a number n which added to its sum of digits gives 21289400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21289409) 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, 2639 + ... + 7038.

Almost surely, 2^21289400 is an apocalyptic number.

21289400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21289400 is an abundant number, since it is smaller than the sum of its proper divisors (32713840).

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

21289400 is a wasteful number, since it uses less digits than its factorization.

21289400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9704 (or 9695 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21289400 is about 4614.0437795929. The cubic root of 21289400 is about 277.1539934489.

The spelling of 21289400 in words is "twenty-one million, two hundred eighty-nine thousand, four hundred".