21353015421 has 8 divisors (see below), whose sum is σ = 31634096960. Its totient is φ = 14235343596.

The previous prime is 21353015371. The next prime is 21353015447. The reversal of 21353015421 is 12451035312.

It is not a de Polignac number, because 21353015421 - 2¹⁴ = 21352999037 is a prime.

It is a super-3 number, since 3×21353015421³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 790852423 = 21353015421 / (2 + 1 + 3 + 5 + 3 + 0 + 1 + 5 + 4 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21353015921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 395426185 + ... + 395426238.

It is an arithmetic number, because the mean of its divisors is an integer number (3954262120).

Almost surely, 2^21353015421 is an apocalyptic number.

It is an amenable number.

21353015421 is a deficient number, since it is larger than the sum of its proper divisors (10281081539).

21353015421 is an equidigital number, since it uses as much as digits as its factorization.

21353015421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790852432 (or 790852426 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The spelling of 21353015421 in words is "twenty-one billion, three hundred fifty-three million, fifteen thousand, four hundred twenty-one".