21487655 has 16 divisors (see below), whose sum is σ = 29630784. Its totient is φ = 14653440.

The previous prime is 21487597. The next prime is 21487667. The reversal of 21487655 is 55678412.

It is not a de Polignac number, because 21487655 - 2⁶ = 21487591 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5165 + ... + 8345.

It is an arithmetic number, because the mean of its divisors is an integer number (1851924).

Almost surely, 2^21487655 is an apocalyptic number.

21487655 is a deficient number, since it is larger than the sum of its proper divisors (8143129).

21487655 is a wasteful number, since it uses less digits than its factorization.

21487655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3386.

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

The square root of 21487655 is about 4635.4778610193. The cubic root of 21487655 is about 278.0116578104.

The spelling of 21487655 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred fifty-five".