421721019 has 16 divisors (see below), whose sum is σ = 628016800. Its totient is φ = 279687168.

The previous prime is 421721009. The next prime is 421721029. The reversal of 421721019 is 910127124.

It is an interprime number because it is at equal distance from previous prime (421721009) and next prime (421721029).

It is not a de Polignac number, because 421721019 - 2¹⁶ = 421655483 is a prime.

It is a super-2 number, since 2×421721019² = 355697235732796722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 421720983 and 421721001.

It is not an unprimeable number, because it can be changed into a prime (421721009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35254 + ... + 45675.

It is an arithmetic number, because the mean of its divisors is an integer number (39251050).

Almost surely, 2^421721019 is an apocalyptic number.

421721019 is a deficient number, since it is larger than the sum of its proper divisors (206295781).

421721019 is a wasteful number, since it uses less digits than its factorization.

421721019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81131 (or 81125 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 421721019 is about 20535.8471702533. The cubic root of 421721019 is about 749.9087408962.

The spelling of 421721019 in words is "four hundred twenty-one million, seven hundred twenty-one thousand, nineteen".