21501019 has 4 divisors (see below), whose sum is σ = 21518640. Its totient is φ = 21483400.

The previous prime is 21500953. The next prime is 21501023. The reversal of 21501019 is 91010512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21501019 - 2¹⁹ = 20976731 is a prime.

It is a super-2 number, since 2×21501019² = 924587636076722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21500987 and 21501005.

It is not an unprimeable number, because it can be changed into a prime (21501059) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6832 + ... + 9469.

It is an arithmetic number, because the mean of its divisors is an integer number (5379660).

Almost surely, 2^21501019 is an apocalyptic number.

21501019 is a deficient number, since it is larger than the sum of its proper divisors (17621).

21501019 is a wasteful number, since it uses less digits than its factorization.

21501019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17620.

The product of its (nonzero) digits is 90, while the sum is 19.

The square root of 21501019 is about 4636.9191280418. The cubic root of 21501019 is about 278.0692812508.

The spelling of 21501019 in words is "twenty-one million, five hundred one thousand, nineteen".