21550155501 has 32 divisors (see below), whose sum is σ = 33651616768. Its totient is φ = 12010239360.

The previous prime is 21550155493. The next prime is 21550155503. The reversal of 21550155501 is 10555105512.

It is not a de Polignac number, because 21550155501 - 2³ = 21550155493 is a prime.

It is a super-2 number, since 2×21550155501² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550155503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 606705 + ... + 641241.

It is an arithmetic number, because the mean of its divisors is an integer number (1051613024).

Almost surely, 2^21550155501 is an apocalyptic number.

21550155501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21550155501 is a deficient number, since it is larger than the sum of its proper divisors (12101461267).

21550155501 is a wasteful number, since it uses less digits than its factorization.

21550155501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35281.

The product of its (nonzero) digits is 6250, while the sum is 30.

The spelling of 21550155501 in words is "twenty-one billion, five hundred fifty million, one hundred fifty-five thousand, five hundred one".