721645423400 has 48 divisors (see below), whose sum is σ = 1830355215840. Its totient is φ = 262416516800.

The previous prime is 721645423397. The next prime is 721645423409. The reversal of 721645423400 is 4324546127.

It is a happy number.

It is a super-2 number, since 2×721645423400² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (721645423409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 164008124 + ... + 164012523.

It is an arithmetic number, because the mean of its divisors is an integer number (38132400330).

Almost surely, 2^721645423400 is an apocalyptic number.

It is an amenable number.

721645423400 is an abundant number, since it is smaller than the sum of its proper divisors (1108709792440).

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

721645423400 is a wasteful number, since it uses less digits than its factorization.

721645423400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328020674 (or 328020665 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 38.

Adding to 721645423400 its reverse (4324546127), we get a palindrome (725969969527).

The spelling of 721645423400 in words is "seven hundred twenty-one billion, six hundred forty-five million, four hundred twenty-three thousand, four hundred".