21515520420454 has 32 divisors (see below), whose sum is σ = 34271308461600. Its totient is φ = 10095442672128.

The previous prime is 21515520420439. The next prime is 21515520420467. The reversal of 21515520420454 is 45402402551512.

It is a super-2 number, since 2×21515520420454² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 371459904 + ... + 371517820.

It is an arithmetic number, because the mean of its divisors is an integer number (1070978389425).

Almost surely, 2^{21515520420454} is an apocalyptic number.

21515520420454 is a deficient number, since it is larger than the sum of its proper divisors (12755788041146).

21515520420454 is a wasteful number, since it uses less digits than its factorization.

21515520420454 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89592.

The product of its (nonzero) digits is 320000, while the sum is 40.

Adding to 21515520420454 its reverse (45402402551512), we get a palindrome (66917922971966).

The spelling of 21515520420454 in words is "twenty-one trillion, five hundred fifteen billion, five hundred twenty million, four hundred twenty thousand, four hundred fifty-four".