21878470 has 32 divisors (see below), whose sum is σ = 41860800. Its totient is φ = 8217216.

The previous prime is 21878459. The next prime is 21878491. The reversal of 21878470 is 7487812.

It is a Harshad number since it is a multiple of its sum of digits (37).

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, 9711 + ... + 11749.

It is an arithmetic number, because the mean of its divisors is an integer number (1308150).

Almost surely, 2^21878470 is an apocalyptic number.

21878470 is a deficient number, since it is larger than the sum of its proper divisors (19982330).

21878470 is a wasteful number, since it uses less digits than its factorization.

21878470 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2112.

The product of its (nonzero) digits is 25088, while the sum is 37.

The square root of 21878470 is about 4677.4426773612. The cubic root of 21878470 is about 279.6870227409.

The spelling of 21878470 in words is "twenty-one million, eight hundred seventy-eight thousand, four hundred seventy".