145611721 has 2 divisors, whose sum is σ = 145611722. Its totient is φ = 145611720.

The previous prime is 145611709. The next prime is 145611727. The reversal of 145611721 is 127116541.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 140683321 + 4928400 = 11861^2 + 2220^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-145611721 is a prime.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 145611721.

It is not a weakly prime, because it can be changed into another prime (145611727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 72805860 + 72805861.

It is an arithmetic number, because the mean of its divisors is an integer number (72805861).

Almost surely, 2^145611721 is an apocalyptic number.

It is an amenable number.

145611721 is a deficient number, since it is larger than the sum of its proper divisors (1).

145611721 is an equidigital number, since it uses as much as digits as its factorization.

145611721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 28.

The square root of 145611721 is about 12066.9681776327. The cubic root of 145611721 is about 526.0965392642.

The spelling of 145611721 in words is "one hundred forty-five million, six hundred eleven thousand, seven hundred twenty-one".