21400788 has 24 divisors (see below), whose sum is σ = 51546880. Its totient is φ = 6903360.

The previous prime is 21400781. The next prime is 21400793. The reversal of 21400788 is 88700412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28393 + ... + 29136.

Almost surely, 2^21400788 is an apocalyptic number.

It is an amenable number.

21400788 is an abundant number, since it is smaller than the sum of its proper divisors (30146092).

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

21400788 is a wasteful number, since it uses less digits than its factorization.

21400788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57567 (or 57565 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21400788 is about 4626.0985722312. The cubic root of 21400788 is about 277.6365175213.

The spelling of 21400788 in words is "twenty-one million, four hundred thousand, seven hundred eighty-eight".