21385253044 has 36 divisors (see below), whose sum is σ = 39115500480. Its totient is φ = 10227149280.

The previous prime is 21385253023. The next prime is 21385253093. The reversal of 21385253044 is 44035258312.

It is a super-2 number, since 2×21385253044² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a junction number, because it is equal to n+sod(n) for n = 21385252994 and 21385253012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 289989 + ... + 356179.

It is an arithmetic number, because the mean of its divisors is an integer number (1086541680).

Almost surely, 2^21385253044 is an apocalyptic number.

It is an amenable number.

21385253044 is a deficient number, since it is larger than the sum of its proper divisors (17730247436).

21385253044 is a wasteful number, since it uses less digits than its factorization.

21385253044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66328 (or 66289 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 37.

The spelling of 21385253044 in words is "twenty-one billion, three hundred eighty-five million, two hundred fifty-three thousand, forty-four".