21229478026778 has 32 divisors (see below), whose sum is σ = 36416895649920. Its totient is φ = 9092473266240.

The previous prime is 21229478026777. The next prime is 21229478026781. The reversal of 21229478026778 is 87762087492212.

It is a super-2 number, since 2×21229478026778² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21229478026777) 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, 155050913 + ... + 155187771.

It is an arithmetic number, because the mean of its divisors is an integer number (1138027989060).

Almost surely, 2^{21229478026778} is an apocalyptic number.

21229478026778 is a deficient number, since it is larger than the sum of its proper divisors (15187417623142).

21229478026778 is a wasteful number, since it uses less digits than its factorization.

21229478026778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143942.

The product of its (nonzero) digits is 75866112, while the sum is 65.

The spelling of 21229478026778 in words is "twenty-one trillion, two hundred twenty-nine billion, four hundred seventy-eight million, twenty-six thousand, seven hundred seventy-eight".