21121738 has 16 divisors (see below), whose sum is σ = 35131680. Its totient is φ = 9442800.

The previous prime is 21121699. The next prime is 21121739. The reversal of 21121738 is 83712112.

It is a happy number.

It is a super-2 number, since 2×21121738² = 892255632281288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21121739) 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, 6528 + ... + 9211.

It is an arithmetic number, because the mean of its divisors is an integer number (2195730).

Almost surely, 2^21121738 is an apocalyptic number.

21121738 is a deficient number, since it is larger than the sum of its proper divisors (14009942).

21121738 is a wasteful number, since it uses less digits than its factorization.

21121738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15813.

The product of its digits is 672, while the sum is 25.

The square root of 21121738 is about 4595.8392051942. The cubic root of 21121738 is about 276.4245112624.

The spelling of 21121738 in words is "twenty-one million, one hundred twenty-one thousand, seven hundred thirty-eight".