21021210209978 has 8 divisors (see below), whose sum is σ = 34398343980000. Its totient is φ = 9555095549980.

The previous prime is 21021210209959. The next prime is 21021210209981. The reversal of 21021210209978 is 87990201212012.

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

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 477754777478 + ... + 477754777521.

It is an arithmetic number, because the mean of its divisors is an integer number (4299792997500).

Almost surely, 2^{21021210209978} is an apocalyptic number.

21021210209978 is a deficient number, since it is larger than the sum of its proper divisors (13377133770022).

21021210209978 is a wasteful number, since it uses less digits than its factorization.

21021210209978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 955509555012.

The product of its (nonzero) digits is 72576, while the sum is 44.

The spelling of 21021210209978 in words is "twenty-one trillion, twenty-one billion, two hundred ten million, two hundred nine thousand, nine hundred seventy-eight".