142491721 has 4 divisors (see below), whose sum is σ = 143021700. Its totient is φ = 141961744.

The previous prime is 142491653. The next prime is 142491737. The reversal of 142491721 is 127194241.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15681600 + 126810121 = 3960^2 + 11261^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-142491721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (142491521) 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, 264586 + ... + 265123.

It is an arithmetic number, because the mean of its divisors is an integer number (35755425).

Almost surely, 2^142491721 is an apocalyptic number.

It is an amenable number.

142491721 is a deficient number, since it is larger than the sum of its proper divisors (529979).

142491721 is an equidigital number, since it uses as much as digits as its factorization.

142491721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529978.

The product of its digits is 4032, while the sum is 31.

The square root of 142491721 is about 11936.9896121258. The cubic root of 142491721 is about 522.3118478854.

The spelling of 142491721 in words is "one hundred forty-two million, four hundred ninety-one thousand, seven hundred twenty-one".