21425321421 has 48 divisors (see below), whose sum is σ = 36775624704. Its totient is φ = 12210703344.

The previous prime is 21425321381. The next prime is 21425321429. The reversal of 21425321421 is 12412352412.

21425321421 is a `hidden beast` number, since 2 + 1 + 425 + 3 + 214 + 21 = 666.

It is not a de Polignac number, because 21425321421 - 2²¹ = 21423224269 is a prime.

It is a super-2 number, since 2×21425321421² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21425321429) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 635040 + ... + 667926.

It is an arithmetic number, because the mean of its divisors is an integer number (766158848).

Almost surely, 2^21425321421 is an apocalyptic number.

21425321421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21425321421 is a deficient number, since it is larger than the sum of its proper divisors (15350303283).

21425321421 is an equidigital number, since it uses as much as digits as its factorization.

21425321421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33292 (or 33280 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

Adding to 21425321421 its reverse (12412352412), we get a palindrome (33837673833).

The spelling of 21425321421 in words is "twenty-one billion, four hundred twenty-five million, three hundred twenty-one thousand, four hundred twenty-one".