21450220 has 24 divisors (see below), whose sum is σ = 49141008. Its totient is φ = 7800000.

The previous prime is 21450211. The next prime is 21450229. The reversal of 21450220 is 2205412.

21450220 = T₃₂₇ + T₃₂₈ + ... + T₅₄₆.

It is an interprime number because it is at equal distance from previous prime (21450211) and next prime (21450229).

It is a super-2 number, since 2×21450220² = 920223876096800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21450194 and 21450203.

It is not an unprimeable number, because it can be changed into a prime (21450229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48531 + ... + 48970.

It is an arithmetic number, because the mean of its divisors is an integer number (2047542).

Almost surely, 2^21450220 is an apocalyptic number.

21450220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21450220 is an abundant number, since it is smaller than the sum of its proper divisors (27690788).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21450220 is a wasteful number, since it uses less digits than its factorization.

21450220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97521 (or 97519 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21450220 is about 4631.4382215463. The cubic root of 21450220 is about 277.8501167450.

Adding to 21450220 its reverse (2205412), we get a palindrome (23655632).

It can be divided in two parts, 21 and 450220, that added together give a square (450241 = 671²).

The spelling of 21450220 in words is "twenty-one million, four hundred fifty thousand, two hundred twenty".