137975621666 has 4 divisors (see below), whose sum is σ = 206963432502. Its totient is φ = 68987810832.

The previous prime is 137975621647. The next prime is 137975621699. The reversal of 137975621666 is 666126579731.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666126579731 = 4519 ⋅147405749.

It can be written as a sum of positive squares in only one way, i.e., 131059204441 + 6916417225 = 362021^2 + 83165^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34493905415 + ... + 34493905418.

Almost surely, 2^137975621666 is an apocalyptic number.

137975621666 is a deficient number, since it is larger than the sum of its proper divisors (68987810836).

137975621666 is an equidigital number, since it uses as much as digits as its factorization.

137975621666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68987810835.

The product of its digits is 17146080, while the sum is 59.

The spelling of 137975621666 in words is "one hundred thirty-seven billion, nine hundred seventy-five million, six hundred twenty-one thousand, six hundred sixty-six".