21014515421 has 4 divisors (see below), whose sum is σ = 21015253344. Its totient is φ = 21013777500.

The previous prime is 21014515391. The next prime is 21014515453. The reversal of 21014515421 is 12451541012.

It is a happy number.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21014515421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21014515471) 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, 324455 + ... + 383796.

It is an arithmetic number, because the mean of its divisors is an integer number (5253813336).

Almost surely, 2^21014515421 is an apocalyptic number.

It is an amenable number.

21014515421 is a deficient number, since it is larger than the sum of its proper divisors (737923).

21014515421 is an equidigital number, since it uses as much as digits as its factorization.

21014515421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 737922.

The product of its (nonzero) digits is 1600, while the sum is 26.

The spelling of 21014515421 in words is "twenty-one billion, fourteen million, five hundred fifteen thousand, four hundred twenty-one".