137432721 has 4 divisors (see below), whose sum is σ = 183243632. Its totient is φ = 91621812.

The previous prime is 137432717. The next prime is 137432723. The reversal of 137432721 is 127234731.

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.

It is not a de Polignac number, because 137432721 - 2² = 137432717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (137432723) 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, 22905451 + ... + 22905456.

It is an arithmetic number, because the mean of its divisors is an integer number (45810908).

Almost surely, 2^137432721 is an apocalyptic number.

It is an amenable number.

137432721 is a deficient number, since it is larger than the sum of its proper divisors (45810911).

137432721 is an equidigital number, since it uses as much as digits as its factorization.

137432721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45810910.

The product of its digits is 7056, while the sum is 30.

The square root of 137432721 is about 11723.1702623480. The cubic root of 137432721 is about 516.0558612380.

The spelling of 137432721 in words is "one hundred thirty-seven million, four hundred thirty-two thousand, seven hundred twenty-one".