21400687 has 16 divisors (see below), whose sum is σ = 26784000. Its totient is φ = 16611840.

The previous prime is 21400681. The next prime is 21400723. The reversal of 21400687 is 78600412.

It is not a de Polignac number, because 21400687 - 2¹⁵ = 21367919 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34264 + ... + 34882.

It is an arithmetic number, because the mean of its divisors is an integer number (1674000).

Almost surely, 2^21400687 is an apocalyptic number.

21400687 is a deficient number, since it is larger than the sum of its proper divisors (5383313).

21400687 is a wasteful number, since it uses less digits than its factorization.

21400687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21400687 is about 4626.0876558924. The cubic root of 21400687 is about 277.6360807565.

The spelling of 21400687 in words is "twenty-one million, four hundred thousand, six hundred eighty-seven".