21101890 has 8 divisors (see below), whose sum is σ = 37983420. Its totient is φ = 8440752.

The previous prime is 21101887. The next prime is 21101903. The reversal of 21101890 is 9810112.

It can be written as a sum of positive squares in 2 ways, for example, as 21095649 + 6241 = 4593^2 + 79^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1055085 + ... + 1055104.

Almost surely, 2^21101890 is an apocalyptic number.

21101890 is a deficient number, since it is larger than the sum of its proper divisors (16881530).

21101890 is a wasteful number, since it uses less digits than its factorization.

21101890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2110196.

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 21101890 is about 4593.6793531983. The cubic root of 21101890 is about 276.3378991800.

The spelling of 21101890 in words is "twenty-one million, one hundred one thousand, eight hundred ninety".