21019019634 has 24 divisors (see below), whose sum is σ = 45689563920. Its totient is φ = 6983516088.

The previous prime is 21019019633. The next prime is 21019019641. The reversal of 21019019634 is 43691091012.

It is a happy number.

21019019634 is a `hidden beast` number, since 2 + 1 + 0 + 1 + 9 + 0 + 19 + 634 = 666.

It is not an unprimeable number, because it can be changed into a prime (21019019633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1896304 + ... + 1907355.

It is an arithmetic number, because the mean of its divisors is an integer number (1903731830).

Almost surely, 2^21019019634 is an apocalyptic number.

21019019634 is an abundant number, since it is smaller than the sum of its proper divisors (24670544286).

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

21019019634 is a wasteful number, since it uses less digits than its factorization.

21019019634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3803974 (or 3803971 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The spelling of 21019019634 in words is "twenty-one billion, nineteen million, nineteen thousand, six hundred thirty-four".