9721945 has 4 divisors (see below), whose sum is σ = 11666340. Its totient is φ = 7777552.

The previous prime is 9721937. The next prime is 9721951. The reversal of 9721945 is 5491279.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5491279 = 73 ⋅75223.

It can be written as a sum of positive squares in 2 ways, for example, as 2082249 + 7639696 = 1443^2 + 2764^2 .

It is a cyclic number.

It is not a de Polignac number, because 9721945 - 2³ = 9721937 is a prime.

9721945 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 972190 + ... + 972199.

It is an arithmetic number, because the mean of its divisors is an integer number (2916585).

Almost surely, 2^9721945 is an apocalyptic number.

It is an amenable number.

9721945 is a deficient number, since it is larger than the sum of its proper divisors (1944395).

9721945 is a wasteful number, since it uses less digits than its factorization.

9721945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1944394.

The product of its digits is 22680, while the sum is 37.

The square root of 9721945 is about 3118.0033675415. The cubic root of 9721945 is about 213.4278322120.

It can be divided in two parts, 972 and 1945, that multiplied together give a triangular number (1890540 = T₁₉₄₄).

The spelling of 9721945 in words is "nine million, seven hundred twenty-one thousand, nine hundred forty-five".