21520081 has 8 divisors (see below), whose sum is σ = 24022944. Its totient is φ = 19108320.

The previous prime is 21520069. The next prime is 21520091. The reversal of 21520081 is 18002512.

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

It is not a de Polignac number, because 21520081 - 2¹¹ = 21518033 is a prime.

It is a super-2 number, since 2×21520081² = 926227772493122, which contains 22 as substring.

It is a pancake number, because a pancake can be divided into 21520081 parts by 6560 straight cuts.

It is not an unprimeable number, because it can be changed into a prime (21520021) 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, 22276 + ... + 23221.

It is an arithmetic number, because the mean of its divisors is an integer number (3002868).

Almost surely, 2^21520081 is an apocalyptic number.

It is an amenable number.

21520081 is a deficient number, since it is larger than the sum of its proper divisors (2502863).

21520081 is a wasteful number, since it uses less digits than its factorization.

21520081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45551.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 21520081 is about 4638.9741322840. The cubic root of 21520081 is about 278.1514322562.

Adding to 21520081 its reverse (18002512), we get a palindrome (39522593).

The spelling of 21520081 in words is "twenty-one million, five hundred twenty thousand, eighty-one".