72161251 has 4 divisors (see below), whose sum is σ = 74649600. Its totient is φ = 69672904.

The previous prime is 72161237. The next prime is 72161269. The reversal of 72161251 is 15216127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15216127 = 181 ⋅84067.

It is a cyclic number.

It is not a de Polignac number, because 72161251 - 2⁷ = 72161123 is a prime.

It is a super-2 number, since 2×72161251² = 10414492291770002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72164251) 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, 1244131 + ... + 1244188.

It is an arithmetic number, because the mean of its divisors is an integer number (18662400).

Almost surely, 2^72161251 is an apocalyptic number.

72161251 is a deficient number, since it is larger than the sum of its proper divisors (2488349).

72161251 is a wasteful number, since it uses less digits than its factorization.

72161251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2488348.

The product of its digits is 840, while the sum is 25.

The square root of 72161251 is about 8494.7778664306. Note that the first 3 decimals coincide. The cubic root of 72161251 is about 416.3271030447.

Adding to 72161251 its product of digits (840), we get a triangular number (72162091 = T₁₂₀₁₃).

Adding to 72161251 its reverse (15216127), we get a palindrome (87377378).

The spelling of 72161251 in words is "seventy-two million, one hundred sixty-one thousand, two hundred fifty-one".