72040921 has 4 divisors (see below), whose sum is σ = 72098100. Its totient is φ = 71983744.

The previous prime is 72040907. The next prime is 72040933. The reversal of 72040921 is 12904027.

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 61387225 + 10653696 = 7835^2 + 3264^2 .

It is a cyclic number.

It is not a de Polignac number, because 72040921 - 2¹³ = 72032729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72040421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26656 + ... + 29233.

It is an arithmetic number, because the mean of its divisors is an integer number (18024525).

Almost surely, 2^72040921 is an apocalyptic number.

It is an amenable number.

72040921 is a deficient number, since it is larger than the sum of its proper divisors (57179).

72040921 is a wasteful number, since it uses less digits than its factorization.

72040921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57178.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 72040921 is about 8487.6923247724. The cubic root of 72040921 is about 416.0955636747.

Adding to 72040921 its reverse (12904027), we get a palindrome (84944948).

The spelling of 72040921 in words is "seventy-two million, forty thousand, nine hundred twenty-one".