21001543450 has 24 divisors (see below), whose sum is σ = 39894000192. Its totient is φ = 8221879920.

The previous prime is 21001543421. The next prime is 21001543457. The reversal of 21001543450 is 5434510012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21001543457) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4466064 + ... + 4470763.

It is an arithmetic number, because the mean of its divisors is an integer number (1662250008).

Almost surely, 2^21001543450 is an apocalyptic number.

21001543450 is a deficient number, since it is larger than the sum of its proper divisors (18892456742).

21001543450 is a wasteful number, since it uses less digits than its factorization.

21001543450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8936886 (or 8936881 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

The spelling of 21001543450 in words is "twenty-one billion, one million, five hundred forty-three thousand, four hundred fifty".