21402222451 has 4 divisors (see below), whose sum is σ = 21418425304. Its totient is φ = 21386019600.

The previous prime is 21402222433. The next prime is 21402222461. The reversal of 21402222451 is 15422220412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21402222451 - 2⁷ = 21402222323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21402222461) 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, 8099445 + ... + 8102086.

It is an arithmetic number, because the mean of its divisors is an integer number (5354606326).

Almost surely, 2^21402222451 is an apocalyptic number.

21402222451 is a deficient number, since it is larger than the sum of its proper divisors (16202853).

21402222451 is a wasteful number, since it uses less digits than its factorization.

21402222451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16202852.

The product of its (nonzero) digits is 2560, while the sum is 25.

Adding to 21402222451 its reverse (15422220412), we get a palindrome (36824442863).

The spelling of 21402222451 in words is "twenty-one billion, four hundred two million, two hundred twenty-two thousand, four hundred fifty-one".