72221651 has 4 divisors (see below), whose sum is σ = 72309600. Its totient is φ = 72133704.

The previous prime is 72221647. The next prime is 72221671. The reversal of 72221651 is 15612227.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15612227 = 1613 ⋅9679.

It is a cyclic number.

It is not a de Polignac number, because 72221651 - 2² = 72221647 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72221651.

It is not an unprimeable number, because it can be changed into a prime (72221671) 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, 42731 + ... + 44388.

It is an arithmetic number, because the mean of its divisors is an integer number (18077400).

Almost surely, 2^72221651 is an apocalyptic number.

72221651 is a deficient number, since it is larger than the sum of its proper divisors (87949).

72221651 is an equidigital number, since it uses as much as digits as its factorization.

72221651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87948.

The product of its digits is 1680, while the sum is 26.

The square root of 72221651 is about 8498.3322481532. The cubic root of 72221651 is about 416.4432278995.

Adding to 72221651 its reverse (15612227), we get a palindrome (87833878).

The spelling of 72221651 in words is "seventy-two million, two hundred twenty-one thousand, six hundred fifty-one".