21020153421 has 32 divisors (see below), whose sum is σ = 29888801280. Its totient is φ = 13094544384.

The previous prime is 21020153327. The next prime is 21020153423. The reversal of 21020153421 is 12435102012.

It is a de Polignac number, because none of the positive numbers 2^k-21020153421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020153423) 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 31 ways as a sum of consecutive naturals, for example, 9165951 + ... + 9168243.

It is an arithmetic number, because the mean of its divisors is an integer number (934025040).

Almost surely, 2^21020153421 is an apocalyptic number.

It is an amenable number.

21020153421 is a deficient number, since it is larger than the sum of its proper divisors (8868647859).

21020153421 is a wasteful number, since it uses less digits than its factorization.

21020153421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3525.

The product of its (nonzero) digits is 480, while the sum is 21.

Adding to 21020153421 its reverse (12435102012), we get a palindrome (33455255433).

The spelling of 21020153421 in words is "twenty-one billion, twenty million, one hundred fifty-three thousand, four hundred twenty-one".