21621405506411 has 4 divisors (see below), whose sum is σ = 21623138975592. Its totient is φ = 21619672037232.

The previous prime is 21621405506387. The next prime is 21621405506429. The reversal of 21621405506411 is 11460550412612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21621405506411 - 2⁶ = 21621405506347 is a prime.

It is a super-2 number, since 2×21621405506411² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21621405506111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866715881 + ... + 866740826.

It is an arithmetic number, because the mean of its divisors is an integer number (5405784743898).

Almost surely, 2^{21621405506411} is an apocalyptic number.

21621405506411 is a deficient number, since it is larger than the sum of its proper divisors (1733469181).

21621405506411 is a wasteful number, since it uses less digits than its factorization.

21621405506411 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1733469180.

The product of its (nonzero) digits is 57600, while the sum is 38.

The spelling of 21621405506411 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred five million, five hundred six thousand, four hundred eleven".