21690019 has 8 divisors (see below), whose sum is σ = 23574320. Its totient is φ = 19836576.

The previous prime is 21690013. The next prime is 21690037. The reversal of 21690019 is 91009612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21690019 is a prime.

It is a super-2 number, since 2×21690019² = 940913848440722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21690013) 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, 6237 + ... + 9070.

It is an arithmetic number, because the mean of its divisors is an integer number (2946790).

Almost surely, 2^21690019 is an apocalyptic number.

21690019 is a deficient number, since it is larger than the sum of its proper divisors (1884301).

21690019 is a wasteful number, since it uses less digits than its factorization.

21690019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15429.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 21690019 is about 4657.2544487069. The cubic root of 21690019 is about 278.8816745369.

Adding to 21690019 its product of nonzero digits (972), we get a triangular number (21690991 = T₆₅₈₆).

The spelling of 21690019 in words is "twenty-one million, six hundred ninety thousand, nineteen".