21537421408 has 12 divisors (see below), whose sum is σ = 42401798460. Its totient is φ = 10768710688.

The previous prime is 21537421403. The next prime is 21537421439. The reversal of 21537421408 is 80412473512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537421403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336522178 + ... + 336522241.

It is an arithmetic number, because the mean of its divisors is an integer number (3533483205).

Almost surely, 2^21537421408 is an apocalyptic number.

It is an amenable number.

21537421408 is a deficient number, since it is larger than the sum of its proper divisors (20864377052).

21537421408 is an equidigital number, since it uses as much as digits as its factorization.

21537421408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673044429 (or 673044421 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 37.

The spelling of 21537421408 in words is "twenty-one billion, five hundred thirty-seven million, four hundred twenty-one thousand, four hundred eight".