21623522061551 has 4 divisors (see below), whose sum is σ = 22150925038704. Its totient is φ = 21096119084400.

The previous prime is 21623522061517. The next prime is 21623522061571. The reversal of 21623522061551 is 15516022532612.

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 21623522061551 - 2²² = 21623517867247 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41), and also a Moran number because the ratio is a prime number: 527402977111 = 21623522061551 / (2 + 1 + 6 + 2 + 3 + 5 + 2 + 2 + 0 + 6 + 1 + 5 + 5 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21623522061499 and 21623522061508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623522061571) 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, 263701488515 + ... + 263701488596.

It is an arithmetic number, because the mean of its divisors is an integer number (5537731259676).

Almost surely, 2^{21623522061551} is an apocalyptic number.

21623522061551 is a deficient number, since it is larger than the sum of its proper divisors (527402977153).

21623522061551 is an equidigital number, since it uses as much as digits as its factorization.

21623522061551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527402977152.

The product of its (nonzero) digits is 216000, while the sum is 41.

The spelling of 21623522061551 in words is "twenty-one trillion, six hundred twenty-three billion, five hundred twenty-two million, sixty-one thousand, five hundred fifty-one".