21519881 has 8 divisors (see below), whose sum is σ = 22511040. Its totient is φ = 20533392.

The previous prime is 21519877. The next prime is 21519907. The reversal of 21519881 is 18891512.

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 21519881 - 2² = 21519877 is a prime.

It is a super-2 number, since 2×21519881² = 926210556508322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21519811) 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, 11135 + ... + 12923.

It is an arithmetic number, because the mean of its divisors is an integer number (2813880).

Almost surely, 2^21519881 is an apocalyptic number.

It is an amenable number.

21519881 is a deficient number, since it is larger than the sum of its proper divisors (991159).

21519881 is a wasteful number, since it uses less digits than its factorization.

21519881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2335.

The product of its digits is 5760, while the sum is 35.

The square root of 21519881 is about 4638.9525757438. The cubic root of 21519881 is about 278.1505705733.

The spelling of 21519881 in words is "twenty-one million, five hundred nineteen thousand, eight hundred eighty-one".