137405621 has 4 divisors (see below), whose sum is σ = 138315744. Its totient is φ = 136495500.

The previous prime is 137405617. The next prime is 137405623. The reversal of 137405621 is 126504731.

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: 126504731 = 1031 ⋅122701.

It is a cyclic number.

It is not a de Polignac number, because 137405621 - 2² = 137405617 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (137405623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 454835 + ... + 455136.

It is an arithmetic number, because the mean of its divisors is an integer number (34578936).

Almost surely, 2^137405621 is an apocalyptic number.

It is an amenable number.

137405621 is a deficient number, since it is larger than the sum of its proper divisors (910123).

137405621 is an equidigital number, since it uses as much as digits as its factorization.

137405621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910122.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 137405621 is about 11722.0143746713. The cubic root of 137405621 is about 516.0219391048.

The spelling of 137405621 in words is "one hundred thirty-seven million, four hundred five thousand, six hundred twenty-one".