21380507621 has 4 divisors (see below), whose sum is σ = 23324190144. Its totient is φ = 19436825100.

The previous prime is 21380507527. The next prime is 21380507633. The reversal of 21380507621 is 12670508312.

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 not a de Polignac number, because 21380507621 - 2¹⁰ = 21380506597 is a prime.

It is a super-2 number, since 2×21380507621² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380507221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 971841245 + ... + 971841266.

It is an arithmetic number, because the mean of its divisors is an integer number (5831047536).

Almost surely, 2^21380507621 is an apocalyptic number.

It is an amenable number.

21380507621 is a deficient number, since it is larger than the sum of its proper divisors (1943682523).

21380507621 is a wasteful number, since it uses less digits than its factorization.

21380507621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1943682522.

The product of its (nonzero) digits is 20160, while the sum is 35.

The spelling of 21380507621 in words is "twenty-one billion, three hundred eighty million, five hundred seven thousand, six hundred twenty-one".