21202122201978 has 32 divisors (see below), whose sum is σ = 44269998598656. Its totient is φ = 6756721859888.

The previous prime is 21202122201977. The next prime is 21202122201979. The reversal of 21202122201978 is 87910222120212.

It is an interprime number because it is at equal distance from previous prime (21202122201977) and next prime (21202122201979).

It is a super-2 number, since 2×21202122201978² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21202122201977) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38075700 + ... + 38628527.

It is an arithmetic number, because the mean of its divisors is an integer number (1383437456208).

Almost surely, 2^{21202122201978} is an apocalyptic number.

21202122201978 is an abundant number, since it is smaller than the sum of its proper divisors (23067876396678).

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

21202122201978 is a wasteful number, since it uses less digits than its factorization.

21202122201978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76706258.

The product of its (nonzero) digits is 32256, while the sum is 39.

The spelling of 21202122201978 in words is "twenty-one trillion, two hundred two billion, one hundred twenty-two million, two hundred one thousand, nine hundred seventy-eight".