21402232251 has 8 divisors (see below), whose sum is σ = 29777018880. Its totient is φ = 13647800232.

The previous prime is 21402232249. The next prime is 21402232253. The reversal of 21402232251 is 15223220412.

It is an interprime number because it is at equal distance from previous prime (21402232249) and next prime (21402232253).

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

It is not a de Polignac number, because 21402232251 - 2¹ = 21402232249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21402232253) 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, 155088571 + ... + 155088708.

It is an arithmetic number, because the mean of its divisors is an integer number (3722127360).

Almost surely, 2^21402232251 is an apocalyptic number.

21402232251 is a deficient number, since it is larger than the sum of its proper divisors (8374786629).

21402232251 is a wasteful number, since it uses less digits than its factorization.

21402232251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310177305.

The product of its (nonzero) digits is 1920, while the sum is 24.

Adding to 21402232251 its reverse (15223220412), we get a palindrome (36625452663).

The spelling of 21402232251 in words is "twenty-one billion, four hundred two million, two hundred thirty-two thousand, two hundred fifty-one".