21554687 has 16 divisors (see below), whose sum is σ = 27059712. Its totient is φ = 16679520.

The previous prime is 21554681. The next prime is 21554699. The reversal of 21554687 is 78645512.

It is not a de Polignac number, because 21554687 - 2⁴ = 21554671 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21554687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11198 + ... + 12980.

It is an arithmetic number, because the mean of its divisors is an integer number (1691232).

Almost surely, 2^21554687 is an apocalyptic number.

21554687 is a deficient number, since it is larger than the sum of its proper divisors (5505025).

21554687 is a wasteful number, since it uses less digits than its factorization.

21554687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1958.

The product of its digits is 67200, while the sum is 38.

The square root of 21554687 is about 4642.7025534703. The cubic root of 21554687 is about 278.3004489418.

The spelling of 21554687 in words is "twenty-one million, five hundred fifty-four thousand, six hundred eighty-seven".