20915901 has 40 divisors (see below), whose sum is σ = 33221760. Its totient is φ = 13087008.

The previous prime is 20915891. The next prime is 20915911. The reversal of 20915901 is 10951902.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20915891) and next prime (20915911).

It is not a de Polignac number, because 20915901 - 2¹³ = 20907709 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20915911) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 191835 + ... + 191943.

It is an arithmetic number, because the mean of its divisors is an integer number (830544).

Almost surely, 2^20915901 is an apocalyptic number.

It is an amenable number.

20915901 is a deficient number, since it is larger than the sum of its proper divisors (12305859).

20915901 is a wasteful number, since it uses less digits than its factorization.

20915901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247 (or 238 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 20915901 is about 4573.3905365713. The cubic root of 20915901 is about 275.5236348071.

It can be divided in two parts, 209 and 15901, that added together give a triangular number (16110 = T₁₇₉).

The spelling of 20915901 in words is "twenty million, nine hundred fifteen thousand, nine hundred one".