137173921 has 4 divisors (see below), whose sum is σ = 137214000. Its totient is φ = 137133844.

The previous prime is 137173877. The next prime is 137173931. The reversal of 137173921 is 129371731.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 129371731 = 607 ⋅213133.

It is a cyclic number.

It is not a de Polignac number, because 137173921 - 2⁹ = 137173409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (137173931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14371 + ... + 21928.

It is an arithmetic number, because the mean of its divisors is an integer number (34303500).

Almost surely, 2^137173921 is an apocalyptic number.

It is an amenable number.

137173921 is a deficient number, since it is larger than the sum of its proper divisors (40079).

137173921 is an equidigital number, since it uses as much as digits as its factorization.

137173921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40078.

The product of its digits is 7938, while the sum is 34.

The square root of 137173921 is about 11712.1270911820. The cubic root of 137173921 is about 515.7317288758.

The spelling of 137173921 in words is "one hundred thirty-seven million, one hundred seventy-three thousand, nine hundred twenty-one".