21221202421 has 8 divisors (see below), whose sum is σ = 21266512064. Its totient is φ = 21175927200.

The previous prime is 21221202349. The next prime is 21221202461. The reversal of 21221202421 is 12420212212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221202421 - 2⁷ = 21221202293 is a prime.

It is a super-2 number, since 2×21221202421² (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 (21221202461) 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, 1497250 + ... + 1511356.

It is an arithmetic number, because the mean of its divisors is an integer number (2658314008).

Almost surely, 2^21221202421 is an apocalyptic number.

It is an amenable number.

21221202421 is a deficient number, since it is larger than the sum of its proper divisors (45309643).

21221202421 is a wasteful number, since it uses less digits than its factorization.

21221202421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17211.

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21221202421 its reverse (12420212212), we get a palindrome (33641414633).

The spelling of 21221202421 in words is "twenty-one billion, two hundred twenty-one million, two hundred two thousand, four hundred twenty-one".