21225015537 has 16 divisors (see below), whose sum is σ = 30899170560. Its totient is φ = 12852637200.

The previous prime is 21225015529. The next prime is 21225015541. The reversal of 21225015537 is 73551052212.

It is not a de Polignac number, because 21225015537 - 2³ = 21225015529 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 21225015498 and 21225015507.

It is not an unprimeable number, because it can be changed into a prime (21225015527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 235987 + ... + 313272.

It is an arithmetic number, because the mean of its divisors is an integer number (1931198160).

Almost surely, 2^21225015537 is an apocalyptic number.

It is an amenable number.

21225015537 is a deficient number, since it is larger than the sum of its proper divisors (9674155023).

21225015537 is a wasteful number, since it uses less digits than its factorization.

21225015537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 550444.

The product of its (nonzero) digits is 21000, while the sum is 33.

Adding to 21225015537 its reverse (73551052212), we get a palindrome (94776067749).

The spelling of 21225015537 in words is "twenty-one billion, two hundred twenty-five million, fifteen thousand, five hundred thirty-seven".