21421401644 has 12 divisors (see below), whose sum is σ = 37643004168. Its totient is φ = 10666257600.

The previous prime is 21421401623. The next prime is 21421401709. The reversal of 21421401644 is 44610412412.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11109722 + ... + 11111649.

It is an arithmetic number, because the mean of its divisors is an integer number (3136917014).

Almost surely, 2^21421401644 is an apocalyptic number.

It is an amenable number.

21421401644 is a deficient number, since it is larger than the sum of its proper divisors (16221602524).

21421401644 is a wasteful number, since it uses less digits than its factorization.

21421401644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22221616 (or 22221614 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 29.

The spelling of 21421401644 in words is "twenty-one billion, four hundred twenty-one million, four hundred one thousand, six hundred forty-four".