145697721 has 16 divisors (see below), whose sum is σ = 209469120. Its totient is φ = 89547840.

The previous prime is 145697683. The next prime is 145697729. The reversal of 145697721 is 127796541.

It is a happy number.

It is not a de Polignac number, because 145697721 - 2⁷ = 145697593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (145697729) 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, 37990 + ... + 41648.

It is an arithmetic number, because the mean of its divisors is an integer number (13091820).

Almost surely, 2^145697721 is an apocalyptic number.

It is an amenable number.

145697721 is a deficient number, since it is larger than the sum of its proper divisors (63771399).

145697721 is a wasteful number, since it uses less digits than its factorization.

145697721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4696.

The product of its digits is 105840, while the sum is 42.

The square root of 145697721 is about 12070.5310985060. The cubic root of 145697721 is about 526.2000918210.

The spelling of 145697721 in words is "one hundred forty-five million, six hundred ninety-seven thousand, seven hundred twenty-one".