21533137 has 8 divisors (see below), whose sum is σ = 22800960. Its totient is φ = 20278800.

The previous prime is 21533131. The next prime is 21533143. The reversal of 21533137 is 73133512.

It is an interprime number because it is at equal distance from previous prime (21533131) and next prime (21533143).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21533137 - 2⁷ = 21533009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21533131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12 + ... + 6562.

It is an arithmetic number, because the mean of its divisors is an integer number (2850120).

Almost surely, 2^21533137 is an apocalyptic number.

It is an amenable number.

21533137 is a deficient number, since it is larger than the sum of its proper divisors (1267823).

21533137 is a wasteful number, since it uses less digits than its factorization.

21533137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6743.

The product of its digits is 1890, while the sum is 25.

The square root of 21533137 is about 4640.3811265886. The cubic root of 21533137 is about 278.2076713714.

Adding to 21533137 its reverse (73133512), we get a palindrome (94666649).

The spelling of 21533137 in words is "twenty-one million, five hundred thirty-three thousand, one hundred thirty-seven".