145457721 has 16 divisors (see below), whose sum is σ = 215997120. Its totient is φ = 96744960.

The previous prime is 145457717. The next prime is 145457743. The reversal of 145457721 is 127754541.

145457721 is a `hidden beast` number, since 14 + 54 + 577 + 21 = 666.

It is not a de Polignac number, because 145457721 - 2² = 145457717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (145457701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5881 + ... + 18041.

It is an arithmetic number, because the mean of its divisors is an integer number (13499820).

Almost surely, 2^145457721 is an apocalyptic number.

It is an amenable number.

145457721 is a deficient number, since it is larger than the sum of its proper divisors (70539399).

145457721 is a wasteful number, since it uses less digits than its factorization.

145457721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12613 (or 12607 counting only the distinct ones).

The product of its digits is 39200, while the sum is 36.

The square root of 145457721 is about 12060.5854335517. The cubic root of 145457721 is about 525.9110060179.

The spelling of 145457721 in words is "one hundred forty-five million, four hundred fifty-seven thousand, seven hundred twenty-one".