21563478 has 12 divisors (see below), whose sum is σ = 46720908. Its totient is φ = 7187820.

The previous prime is 21563471. The next prime is 21563491. The reversal of 21563478 is 87436512.

21563478 is a `hidden beast` number, since 2 + 15 + 634 + 7 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563471) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 598968 + ... + 599003.

It is an arithmetic number, because the mean of its divisors is an integer number (3893409).

Almost surely, 2^21563478 is an apocalyptic number.

21563478 is an abundant number, since it is smaller than the sum of its proper divisors (25157430).

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

21563478 is a wasteful number, since it uses less digits than its factorization.

21563478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1197979 (or 1197976 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21563478 is about 4643.6492115577. The cubic root of 21563478 is about 278.3382784051.

The spelling of 21563478 in words is "twenty-one million, five hundred sixty-three thousand, four hundred seventy-eight".