721098421 has 4 divisors (see below), whose sum is σ = 731861152. Its totient is φ = 710335692.

The previous prime is 721098377. The next prime is 721098451. The reversal of 721098421 is 124890127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 124890127 = 743 ⋅168089.

It is a cyclic number.

It is not a de Polignac number, because 721098421 - 2¹³ = 721090229 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 (721098451) 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, 5381265 + ... + 5381398.

It is an arithmetic number, because the mean of its divisors is an integer number (182965288).

Almost surely, 2^721098421 is an apocalyptic number.

It is an amenable number.

721098421 is a deficient number, since it is larger than the sum of its proper divisors (10762731).

721098421 is a wasteful number, since it uses less digits than its factorization.

721098421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10762730.

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 721098421 is about 26853.2757964461. The cubic root of 721098421 is about 896.7365019029.

The spelling of 721098421 in words is "seven hundred twenty-one million, ninety-eight thousand, four hundred twenty-one".