721421745 has 32 divisors (see below), whose sum is σ = 1293252480. Its totient is φ = 340323840.

The previous prime is 721421737. The next prime is 721421747. The reversal of 721421745 is 547124127.

It is not a de Polignac number, because 721421745 - 2³ = 721421737 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (721421747) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52980 + ... + 65189.

It is an arithmetic number, because the mean of its divisors is an integer number (40414140).

Almost surely, 2^721421745 is an apocalyptic number.

It is an amenable number.

721421745 is a deficient number, since it is larger than the sum of its proper divisors (571830735).

721421745 is a wasteful number, since it uses less digits than its factorization.

721421745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118225.

The product of its digits is 15680, while the sum is 33.

The square root of 721421745 is about 26859.2953183809. The cubic root of 721421745 is about 896.8705072395.

The spelling of 721421745 in words is "seven hundred twenty-one million, four hundred twenty-one thousand, seven hundred forty-five".