2138566221 has 72 divisors (see below), whose sum is σ = 3647996352. Its totient is φ = 1201939200.

The previous prime is 2138566211. The next prime is 2138566229. The reversal of 2138566221 is 1226658312.

2138566221 = T₇₇₂₆ + T₇₇₂₇ + ... + T₇₇₉₆.

2138566221 is a `hidden beast` number, since 21 + 3 + 8 + 5 + 6 + 622 + 1 = 666.

It is not a de Polignac number, because 2138566221 - 2²³ = 2130177613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2138566229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1313610 + ... + 1315236.

It is an arithmetic number, because the mean of its divisors is an integer number (50666616).

Almost surely, 2^2138566221 is an apocalyptic number.

It is an amenable number.

2138566221 is a deficient number, since it is larger than the sum of its proper divisors (1509430131).

2138566221 is a wasteful number, since it uses less digits than its factorization.

2138566221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1743 (or 1729 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 2138566221 is about 46244.6345103948. The cubic root of 2138566221 is about 1288.3708820073.

The spelling of 2138566221 in words is "two billion, one hundred thirty-eight million, five hundred sixty-six thousand, two hundred twenty-one".