21240266021 has 32 divisors (see below), whose sum is σ = 25335555840. Its totient is φ = 17606882304.

The previous prime is 21240266011. The next prime is 21240266023. The reversal of 21240266021 is 12066204212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21240266021 is a prime.

It is a super-2 number, since 2×21240266021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240266023) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2124791 + ... + 2134763.

It is an arithmetic number, because the mean of its divisors is an integer number (791736120).

Almost surely, 2^21240266021 is an apocalyptic number.

It is an amenable number.

21240266021 is a deficient number, since it is larger than the sum of its proper divisors (4095289819).

21240266021 is a wasteful number, since it uses less digits than its factorization.

21240266021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10445.

The product of its (nonzero) digits is 2304, while the sum is 26.

The spelling of 21240266021 in words is "twenty-one billion, two hundred forty million, two hundred sixty-six thousand, twenty-one".