20278121890 has 64 divisors (see below), whose sum is σ = 40426848000. Its totient is φ = 7276034304.

The previous prime is 20278121861. The next prime is 20278121893. The reversal of 20278121890 is 9812187202.

It is a super-2 number, since 2×20278121890² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20278121893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1103296 + ... + 1121524.

It is an arithmetic number, because the mean of its divisors is an integer number (631669500).

Almost surely, 2^20278121890 is an apocalyptic number.

20278121890 is a deficient number, since it is larger than the sum of its proper divisors (20148726110).

20278121890 is a wasteful number, since it uses less digits than its factorization.

20278121890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18491.

The product of its (nonzero) digits is 32256, while the sum is 40.

The spelling of 20278121890 in words is "twenty billion, two hundred seventy-eight million, one hundred twenty-one thousand, eight hundred ninety".