21661032115021 has 16 divisors (see below), whose sum is σ = 23588985486528. Its totient is φ = 19771553692800.

The previous prime is 21661032114973. The next prime is 21661032115027. The reversal of 21661032115021 is 12051123016612.

It is not a de Polignac number, because 21661032115021 - 2¹⁵ = 21661032082253 is a prime.

It is a super-2 number, since 2×21661032115021² (a number of 27 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 (21661032115027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22153731 + ... + 23110816.

It is an arithmetic number, because the mean of its divisors is an integer number (1474311592908).

Almost surely, 2^{21661032115021} is an apocalyptic number.

It is an amenable number.

21661032115021 is a deficient number, since it is larger than the sum of its proper divisors (1927953371507).

21661032115021 is a wasteful number, since it uses less digits than its factorization.

21661032115021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45264972.

The product of its (nonzero) digits is 4320, while the sum is 31.

The spelling of 21661032115021 in words is "twenty-one trillion, six hundred sixty-one billion, thirty-two million, one hundred fifteen thousand, twenty-one".