21537963 has 48 divisors (see below), whose sum is σ = 35942400. Its totient is φ = 12337920.

The previous prime is 21537961. The next prime is 21537973. The reversal of 21537963 is 36973512.

It is not a de Polignac number, because 21537963 - 2¹ = 21537961 is a prime.

It is a super-3 number, since 3×21537963³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21537961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 89998 + ... + 90236.

It is an arithmetic number, because the mean of its divisors is an integer number (748800).

Almost surely, 2^21537963 is an apocalyptic number.

21537963 is a deficient number, since it is larger than the sum of its proper divisors (14404437).

21537963 is a wasteful number, since it uses less digits than its factorization.

21537963 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312 (or 309 counting only the distinct ones).

The product of its digits is 34020, while the sum is 36.

The square root of 21537963 is about 4640.9010978473. The cubic root of 21537963 is about 278.2284537579.

It can be divided in two parts, 21537 and 963, that added together give a square (22500 = 150²).

The spelling of 21537963 in words is "twenty-one million, five hundred thirty-seven thousand, nine hundred sixty-three".