72121830 has 32 divisors (see below), whose sum is σ = 188828928. Its totient is φ = 17484000.

The previous prime is 72121807. The next prime is 72121831. The reversal of 72121830 is 3812127.

It is an alternating number because its digits alternate between odd and even.

It is a self number, because there is not a number n which added to its sum of digits gives 72121830.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72121831) 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, 108946 + ... + 109605.

It is an arithmetic number, because the mean of its divisors is an integer number (5900904).

Almost surely, 2^72121830 is an apocalyptic number.

72121830 is an abundant number, since it is smaller than the sum of its proper divisors (116707098).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

72121830 is a wasteful number, since it uses less digits than its factorization.

72121830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218572.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 72121830 is about 8492.4572415762. The cubic root of 72121830 is about 416.2512773996.

Adding to 72121830 its reverse (3812127), we get a palindrome (75933957).

The spelling of 72121830 in words is "seventy-two million, one hundred twenty-one thousand, eight hundred thirty".