81203421 has 16 divisors (see below), whose sum is σ = 117380480. Its totient is φ = 49636800.

The previous prime is 81203387. The next prime is 81203431. The reversal of 81203421 is 12430218.

It is not a de Polignac number, because 81203421 - 2⁹ = 81202909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81203431) 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, 1006 + ... + 12783.

It is an arithmetic number, because the mean of its divisors is an integer number (7336280).

Almost surely, 2^81203421 is an apocalyptic number.

It is an amenable number.

81203421 is a deficient number, since it is larger than the sum of its proper divisors (36177059).

81203421 is a wasteful number, since it uses less digits than its factorization.

81203421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13956.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 81203421 is about 9011.2940802085. The cubic root of 81203421 is about 433.0367705903.

Adding to 81203421 its reverse (12430218), we get a palindrome (93633639).

The spelling of 81203421 in words is "eighty-one million, two hundred three thousand, four hundred twenty-one".