1021578426778 has 72 divisors (see below), whose sum is σ = 2043759724092. Its totient is φ = 380367816192.

The previous prime is 1021578426773. The next prime is 1021578426779. The reversal of 1021578426778 is 8776248751201.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 221006232769 + 800572194009 = 470113^2 + 894747^2 .

It is a super-2 number, since 2×1021578426778² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1021578426773) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1532625 + ... + 2095732.

Almost surely, 2^{1021578426778} is an apocalyptic number.

1021578426778 is an abundant number, since it is smaller than the sum of its proper divisors (1022181297314).

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

1021578426778 is a wasteful number, since it uses less digits than its factorization.

1021578426778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3628416 (or 3628396 counting only the distinct ones).

The product of its (nonzero) digits is 10536960, while the sum is 58.

The spelling of 1021578426778 in words is "one trillion, twenty-one billion, five hundred seventy-eight million, four hundred twenty-six thousand, seven hundred seventy-eight".