21004409978 has 8 divisors (see below), whose sum is σ = 33164857920. Its totient is φ = 9949457340.

The previous prime is 21004409977. The next prime is 21004410013. The reversal of 21004409978 is 87990440012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21004409977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276373778 + ... + 276373853.

It is an arithmetic number, because the mean of its divisors is an integer number (4145607240).

Almost surely, 2^21004409978 is an apocalyptic number.

21004409978 is a deficient number, since it is larger than the sum of its proper divisors (12160447942).

21004409978 is a wasteful number, since it uses less digits than its factorization.

21004409978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552747652.

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 21004409978 in words is "twenty-one billion, four million, four hundred nine thousand, nine hundred seventy-eight".