21621212301645 has 48 divisors (see below), whose sum is σ = 40884439699584. Its totient is φ = 10482834384000.

The previous prime is 21621212301613. The next prime is 21621212301653. The reversal of 21621212301645 is 54610321212612.

21621212301645 is a `hidden beast` number, since 2 + 1 + 6 + 2 + 1 + 2 + 1 + 2 + 3 + 0 + 1 + 645 = 666.

It is not a de Polignac number, because 21621212301645 - 2⁵ = 21621212301613 is a prime.

It is a super-3 number, since 3×21621212301645³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 31669440 + ... + 32344950.

It is an arithmetic number, because the mean of its divisors is an integer number (851759160408).

Almost surely, 2^{21621212301645} is an apocalyptic number.

It is an amenable number.

21621212301645 is a deficient number, since it is larger than the sum of its proper divisors (19263227397939).

21621212301645 is a wasteful number, since it uses less digits than its factorization.

21621212301645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740194 (or 740191 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21621212301645 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred twelve million, three hundred one thousand, six hundred forty-five".