21003947994 has 16 divisors (see below), whose sum is σ = 42013104480. Its totient is φ = 7000447920.

The previous prime is 21003947969. The next prime is 21003947999. The reversal of 21003947994 is 49974930012.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21003947999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 163584 + ... + 262235.

It is an arithmetic number, because the mean of its divisors is an integer number (2625819030).

Almost surely, 2^21003947994 is an apocalyptic number.

21003947994 is an abundant number, since it is smaller than the sum of its proper divisors (21009156486).

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

21003947994 is a wasteful number, since it uses less digits than its factorization.

21003947994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434045.

The product of its (nonzero) digits is 489888, while the sum is 48.

The spelling of 21003947994 in words is "twenty-one billion, three million, nine hundred forty-seven thousand, nine hundred ninety-four".