21777222138 has 32 divisors (see below), whose sum is σ = 49965797376. Its totient is φ = 6198402288.

The previous prime is 21777222133. The next prime is 21777222143. The reversal of 21777222138 is 83122277712.

It is an interprime number because it is at equal distance from previous prime (21777222133) and next prime (21777222143).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 21777222138.

It is not an unprimeable number, because it can be changed into a prime (21777222133) 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, 974706 + ... + 996797.

It is an arithmetic number, because the mean of its divisors is an integer number (1561431168).

Almost surely, 2^21777222138 is an apocalyptic number.

21777222138 is an abundant number, since it is smaller than the sum of its proper divisors (28188575238).

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

21777222138 is a wasteful number, since it uses less digits than its factorization.

21777222138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1971778.

The product of its digits is 131712, while the sum is 42.

The spelling of 21777222138 in words is "twenty-one billion, seven hundred seventy-seven million, two hundred twenty-two thousand, one hundred thirty-eight".