21011021999978 has 8 divisors (see below), whose sum is σ = 31519615935168. Its totient is φ = 10504483354924.

The previous prime is 21011021999977. The next prime is 21011022000049. The reversal of 21011021999978 is 87999912011012.

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 (21011021999977) 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, 513796976 + ... + 513837867.

It is an arithmetic number, because the mean of its divisors is an integer number (3939951991896).

Almost surely, 2^{21011021999978} is an apocalyptic number.

21011021999978 is a deficient number, since it is larger than the sum of its proper divisors (10508593935190).

21011021999978 is a wasteful number, since it uses less digits than its factorization.

21011021999978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1027645068.

The product of its (nonzero) digits is 1469664, while the sum is 59.

The spelling of 21011021999978 in words is "twenty-one trillion, eleven billion, twenty-one million, nine hundred ninety-nine thousand, nine hundred seventy-eight".